Live time tissue classification using electrical parameters

ABSTRACT

A radio frequency (RF) instrument may include a method of classifying a tissue in live time. The method may include activating the instrument for a first period of time T 1  when the RF instrument contacts the tissue, plotting at least three electrical parameters associated with the tissue to classify the tissue into distinct groups, and applying a classification algorithm to classify the tissue into a distinct group in live time. The parameters may include an initial impedance of the tissue, a minimum impedance of the tissue, and an amount of time that the impedance slope is ˜0. The instrument may collect the parameters during a predetermined amount of time, such as within the first 0.75 seconds of the activation of the device. The classification algorithm may include a support vector machine algorithm that may use a linear, polynomial, or radial basis set.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. § 119(e)to U.S. Provisional Patent Application Ser. No. 62/640,417, titledTEMPERATURE CONTROL IN ULTRASONIC DEVICE AND CONTROL SYSTEM THEREFOR,filed Mar. 8, 2018, and to U.S. Provisional Patent Application Ser. No.62/640,415, titled ESTIMATING STATE OF ULTRASONIC END EFFECTOR ANDCONTROL SYSTEM THEREFOR, filed Mar. 8, 2018, the disclosure of each ofwhich is herein incorporated by reference in its entirety.

BACKGROUND

In a surgical environment, smart energy devices may be needed in a smartenergy architecture environment. Ultrasonic surgical devices, such asultrasonic scalpels, are finding increasingly widespread applications insurgical procedures by virtue of their unique performancecharacteristics. Depending upon specific device configurations andoperational parameters, ultrasonic surgical devices can providesubstantially simultaneous transection of tissue and homeostasis bycoagulation, desirably minimizing patient trauma. An ultrasonic surgicaldevice may comprise a handpiece containing an ultrasonic transducer, andan instrument coupled to the ultrasonic transducer having adistally-mounted end effector (e.g., a blade tip) to cut and sealtissue. In some cases, the instrument may be permanently affixed to thehandpiece. In other cases, the instrument may be detachable from thehandpiece, as in the case of a disposable instrument or aninterchangeable instrument. The end effector transmits ultrasonic energyto tissue brought into contact with the end effector to realize cuttingand sealing action. Ultrasonic surgical devices of this nature can beconfigured for open surgical use, laparoscopic, or endoscopic surgicalprocedures including robotic-assisted procedures.

Ultrasonic energy cuts and coagulates tissue using temperatures lowerthan those used in electrosurgical procedures and can be transmitted tothe end effector by an ultrasonic generator in communication with thehandpiece. Vibrating at high frequencies (e.g., 55,500 cycles persecond), the ultrasonic blade denatures protein in the tissue to form asticky coagulum. Pressure exerted on tissue by the blade surfacecollapses blood vessels and allows the coagulum to form a hemostaticseal. A surgeon can control the cutting speed and coagulation by theforce applied to the tissue by the end effector, the time over which theforce is applied, and the selected excursion level of the end effector.

The ultrasonic transducer may be modeled as an equivalent circuitcomprising a first branch having a static capacitance and a second“motional” branch having a serially connected inductance, resistance andcapacitance that define the electromechanical properties of a resonator.Known ultrasonic generators may include a tuning inductor for tuning outthe static capacitance at a resonant frequency so that substantially allof a generator's drive signal current flows into the motional branch.Accordingly, by using a tuning inductor, the generator's drive signalcurrent represents the motional branch current, and the generator isthus able to control its drive signal to maintain the ultrasonictransducer's resonant frequency. The tuning inductor may also transformthe phase impedance plot of the ultrasonic transducer to improve thegenerator's frequency lock capabilities. However, the tuning inductormust be matched with the specific static capacitance of an ultrasonictransducer at the operational resonant frequency. In other words, adifferent ultrasonic transducer having a different static capacitancerequires a different tuning inductor.

Additionally, in some ultrasonic generator architectures, thegenerator's drive signal exhibits asymmetrical harmonic distortion thatcomplicates impedance magnitude and phase measurements. For example, theaccuracy of impedance phase measurements may be reduced due to harmonicdistortion in the current and voltage signals.

Moreover, electromagnetic interference in noisy environments decreasesthe ability of the generator to maintain lock on the ultrasonictransducer's resonant frequency, increasing the likelihood of invalidcontrol algorithm inputs.

Electrosurgical devices for applying electrical energy to tissue inorder to treat and/or destroy the tissue are also finding increasinglywidespread applications in surgical procedures. An electrosurgicaldevice may comprise a handpiece and an instrument having adistally-mounted end effector (e.g., one or more electrodes). The endeffector can be positioned against the tissue such that electricalcurrent is introduced into the tissue. Electrosurgical devices can beconfigured for bipolar or monopolar operation. During bipolar operation,current is introduced into and returned from the tissue by active andreturn electrodes, respectively, of the end effector. During monopolaroperation, current is introduced into the tissue by an active electrodeof the end effector and returned through a return electrode (e.g., agrounding pad) separately located on a patient's body. Heat generated bythe current flowing through the tissue may form hemostatic seals withinthe tissue and/or between tissues and thus may be particularly usefulfor sealing blood vessels, for example. The end effector of anelectrosurgical device may also comprise a cutting member that ismovable relative to the tissue and the electrodes to transect thetissue.

Electrical energy applied by an electrosurgical device can betransmitted to the instrument by a generator in communication with thehandpiece. The electrical energy may be in the form of radio frequency(RF) energy. RF energy is a form of electrical energy that may be in thefrequency range of 300 kHz to 1 MHz, as described inEN60601-2-2:2009+A11:2011, Definition 201.3.218—HIGH FREQUENCY. Forexample, the frequencies in monopolar RF applications are typicallyrestricted to less than 5 MHz. However, in bipolar RF applications, thefrequency can be almost any value. Frequencies above 200 kHz aretypically used for monopolar applications in order to avoid the unwantedstimulation of nerves and muscles which would result from the use of lowfrequency current. Lower frequencies may be used for bipolar techniquesif a risk analysis shows the possibility of neuromuscular stimulationhas been mitigated to an acceptable level. Normally, frequencies above 5MHz are not used in order to minimize the problems associated with highfrequency leakage currents. It is generally recognized that 10 mA is thelower threshold of thermal effects on tissue.

During its operation, an electrosurgical device can transmit lowfrequency RF energy through tissue, which causes ionic agitation, orfriction, in effect resistive heating, thereby increasing thetemperature of the tissue. Because a sharp boundary may be createdbetween the affected tissue and the surrounding tissue, surgeons canoperate with a high level of precision and control, without sacrificingun-targeted adjacent tissue. The low operating temperatures of RF energymay be useful for removing, shrinking, or sculpting soft tissue whilesimultaneously sealing blood vessels. RF energy may work particularlywell on connective tissue, which is primarily comprised of collagen andshrinks when contacted by heat.

Due to their unique drive signal, sensing and feedback needs, ultrasonicand electrosurgical devices have generally required differentgenerators. Additionally, in cases where the instrument is disposable orinterchangeable with a handpiece, ultrasonic and electrosurgicalgenerators are limited in their ability to recognize the particularinstrument configuration being used and to optimize control anddiagnostic processes accordingly. Moreover, capacitive coupling betweenthe non-isolated and patient-isolated circuits of the generator,especially in cases where higher voltages and frequencies are used, mayresult in exposure of a patient to unacceptable levels of leakagecurrent.

Furthermore, due to their unique drive signal, sensing and feedbackneeds, ultrasonic and electrosurgical devices have generally requireddifferent user interfaces for the different generators. In suchconventional ultrasonic and electrosurgical devices, one user interfaceis configured for use with an ultrasonic instrument whereas a differentuser interface may be configured for use with an electrosurgicalinstrument. Such user interfaces include hand and/or foot activated userinterfaces such as hand activated switches and/or foot activatedswitches. As various aspects of combined generators for use with bothultrasonic and electrosurgical instruments are contemplated in thesubsequent disclosure, additional user interfaces that are configured tooperate with both ultrasonic and/or electrosurgical instrumentgenerators also are contemplated.

Additional user interfaces for providing feedback, whether to the useror other machine, are contemplated within the subsequent disclosure toprovide feedback indicating an operating mode or status of either anultrasonic and/or electrosurgical instrument. Providing user and/ormachine feedback for operating a combination ultrasonic and/orelectrosurgical instrument will require providing sensory feedback to auser and electrical/mechanical/electro-mechanical feedback to a machine.Feedback devices that incorporate visual feedback devices (e.g., an LCDdisplay screen, LED indicators), audio feedback devices (e.g., aspeaker, a buzzer) or tactile feedback devices (e.g., haptic actuators)for use in combined ultrasonic and/or electrosurgical instruments arecontemplated in the subsequent disclosure.

Other electrical surgical instruments include, without limitation,irreversible and/or reversible electroporation, and/or microwavetechnologies, among others. Accordingly, the techniques disclosed hereinare applicable to ultrasonic, bipolar or monopolar RF (electrosurgical),irreversible and/or reversible electroporation, and/or microwave basedsurgical instruments, among others.

SUMMARY

An aspect of a method of classifying a tissue in live time may includeactivating, by a processor or control circuit, a radio frequency (RF)instrument for a first period of time T1, wherein the RF instrumentcontacts the tissue, plotting, by the processor or control circuit, atleast three electrical parameters associated with the tissue in contactwith the RF instrument to classify the tissue into distinct groups, andapplying, by the processor or control circuit, a classificationalgorithm to classify the tissue into a distinct group in live time.

In one aspect of the method, plotting, by the processor or controlcircuit, at least three electrical parameters associated with the tissuein contact with the RF instrument my include plotting, by the processoror control circuit, an initial RF impedance of the tissue, a minimum RFimpedance of the tissue, and an amount of time in milliseconds that theRF impedance slope is ˜0.

One aspect of the method may further include collecting, by theprocessor or control circuit, data associated with the at least threeelectrical parameters in a predetermined amount of time.

In one aspect of the method, collecting, by the processor or controlcircuit, data associated with the at least three electrical parametersin a predetermined amount of time my include collecting, by theprocessor or control circuit, data associated with the at least threeelectrical parameters in within a first 0.75 seconds after activation ofthe radio frequency (RF) instrument.

In one aspect of the method, applying, by the processor or controlcircuit, a classification algorithm to classify the tissue into adistinct group in live time may include applying, by the processor orcontrol circuit, a classification algorithm to classify the tissue intoa distinct group in live time using a support vector machine algorithm.

In one aspect of the method, applying, by the processor or controlcircuit, a classification algorithm to classify the tissue into adistinct group in live time using a support vector machine algorithm myinclude applying, by the processor or control circuit, a classificationalgorithm to classify the tissue into a distinct group in live timeusing a linear basis function, a polynomial basis function, or a radialbasis function.

In one aspect, the method may further include applying, by the processoror control circuit, an activation algorithm specific to each tissuegroup after the first period T1.

An aspect of a surgical instrument may include a radio frequency (RF)instrument having an end effector and a generator configured to supplypower to the end effector. An aspect of the generator may include acontrol circuit configured to activate the radio frequency (RF)instrument for a first period of time T1, wherein the RF instrumentcontacts the tissue, plot at least three electrical parametersassociated with the tissue in contact with the RF instrument to classifythe tissue into distinct groups, and apply a classification algorithm toclassify the tissue into a distinct group in live time.

In one aspect of the surgical instrument, the at least three electricalparameters associated with the tissue in contact with the RF instrumentmy include an initial RF impedance of the tissue, a minimum RF impedanceof the tissue, and an amount of time in milliseconds that the RFimpedance slope is ˜0.

In one aspect of the surgical instrument, the control circuit is furtherconfigured to collect data associated with the at least three electricalparameters in a predetermined amount of time.

In one aspect of the surgical instrument, the predetermined amount oftime may include a first 0.75 seconds after activation of the radiofrequency (RF) instrument.

In one aspect of the surgical instrument, the control circuit is furtherconfigured to classify the tissue into a distinct group in live timeusing a support vector machine algorithm.

In one aspect of the surgical instrument, the support vector machinealgorithm may include a linear basis function, a polynomial basisfunction, or a radial basis function.

In one aspect of the surgical instrument, the control circuit is furtherconfigured to apply an activation algorithm specific to each tissuegroup after the first period T1.

An aspect of a generator for a surgical instrument in which the surgicalinstrument includes a radio frequency (RF) instrument having an endeffector, may include a control circuit configured to activate the radiofrequency (RF) instrument for a first period of time T1, wherein the RFinstrument contacts a tissue, plot at least three electrical parametersassociated with the tissue in contact with the RF instrument to classifythe tissue into distinct groups, and apply a classification algorithm toclassify the tissue into a distinct group in live time.

In one aspect of the generator for a surgical instrument, the at leastthree electrical parameters associated with the tissue in contact withthe RF instrument may include an initial RF impedance of the tissue, aminimum RF impedance of the tissue, and an amount of time inmilliseconds that the RF impedance slope is ˜0.

In one aspect of the generator for a surgical instrument, the controlcircuit is further configured to collect data associated with the atleast three electrical parameters in a predetermined amount of time.

In one aspect of the generator for a surgical instrument, thepredetermined amount of time comprises a first 0.75 seconds afteractivation of the radio frequency (RF) instrument.

In one aspect of the generator for a surgical instrument, the controlcircuit is further configured to classify the tissue into a distinctgroup in live time using a support vector machine algorithm.

In one aspect of the generator for a surgical instrument, the supportvector machine algorithm may include a linear basis function, apolynomial basis function, or a radial basis function.

In one aspect of the generator for a surgical instrument, the controlcircuit is further configured to apply an activation algorithm specificto each tissue group after the first period T1.

FIGURES

The features of various aspects are set forth with particularity in theappended claims. The various aspects, however, both as to organizationand methods of operation, together with further objects and advantagesthereof, may best be understood by reference to the followingdescription, taken in conjunction with the accompanying drawings asfollows.

FIG. 1 is a system configured to execute adaptive ultrasonic bladecontrol algorithms in a surgical data network comprising a modularcommunication hub, in accordance with at least one aspect of the presentdisclosure.

FIG. 2 illustrates an example of a generator, in accordance with atleast one aspect of the present disclosure.

FIG. 3 is a surgical system comprising a generator and various surgicalinstruments usable therewith, in accordance with at least one aspect ofthe present disclosure.

FIG. 4 is an end effector, in accordance with at least one aspect of thepresent disclosure.

FIG. 5 is a diagram of the surgical system of FIG. 3, in accordance withat least one aspect of the present disclosure.

FIG. 6 is a model illustrating motional branch current, in accordancewith at least one aspect of the present disclosure.

FIG. 7 is a structural view of a generator architecture, in accordancewith at least one aspect of the present disclosure.

FIGS. 8A-8C are functional views of a generator architecture, inaccordance with at least one aspect of the present disclosure.

FIGS. 9A-9B are structural and functional aspects of a generator, inaccordance with at least one aspect of the present disclosure.

FIG. 10 illustrates a control circuit configured to control aspects ofthe surgical instrument or tool, in accordance with at least one aspectof the present disclosure.

FIG. 11 illustrates a combinational logic circuit configured to controlaspects of the surgical instrument or tool, in accordance with at leastone aspect of the present disclosure.

FIG. 12 illustrates a sequential logic circuit configured to controlaspects of the surgical instrument or tool, in accordance with at leastone aspect of the present disclosure.

FIG. 13 illustrates one aspect of a fundamental architecture for adigital synthesis circuit such as a direct digital synthesis (DDS)circuit configured to generate a plurality of wave shapes for theelectrical signal waveform for use in a surgical instrument, inaccordance with at least one aspect of the present disclosure.

FIG. 14 illustrates one aspect of direct digital synthesis (DDS) circuitconfigured to generate a plurality of wave shapes for the electricalsignal waveform for use in surgical instrument, in accordance with atleast one aspect of the present disclosure.

FIG. 15 illustrates one cycle of a discrete time digital electricalsignal waveform, in accordance with at least one aspect of the presentdisclosure of an analog waveform (shown superimposed over a discretetime digital electrical signal waveform for comparison purposes), inaccordance with at least one aspect of the present disclosure.

FIG. 16 is a diagram of a control system in accordance with one aspectof this disclosure.

FIG. 17 illustrates a proportional-integral-derivative (PID) controllerfeedback control system in accordance with one aspect of thisdisclosure.

FIG. 18 is an alternative system for controlling the frequency of anultrasonic electromechanical system and detecting the impedance thereof,in accordance with at least one aspect of the present disclosure.

FIG. 19 is a spectra of the same ultrasonic device with a variety ofdifferent states and conditions of the end effector where phase andmagnitude of the impedance of an ultrasonic transducer are plotted as afunction of frequency, in accordance with at least one aspect of thepresent disclosure.

FIG. 20 is a graphical representation of a plot of a set of 3D trainingdata S, where ultrasonic transducer impedance magnitude and phase areplotted as a function of frequency, in accordance with at least oneaspect of the present disclosure.

FIG. 21 is a logic flow diagram depicting a control program or a logicconfiguration to determine jaw conditions based on the complex impedancecharacteristic pattern (fingerprint), in accordance with at least oneaspect of the present disclosure.

FIG. 22 is a circle plot of complex impedance plotted as an imaginarycomponent versus real components of a piezoelectric vibrator, inaccordance with at least one aspect of the present disclosure.

FIG. 23 is a circle plot of complex admittance plotted as an imaginarycomponent versus real components of a piezoelectric vibrator, inaccordance with at least one aspect of the present disclosure.

FIG. 24 is a circle plot of complex admittance for a 55.5 kHz ultrasonicpiezoelectric transducer.

FIG. 25 is a graphical display of an impedance analyzer showingimpedance/admittance circle plots for an ultrasonic device with the jawopen and no loading where complex admittance is depicted in broken lineand complex impedance is depicted in solid line, in accordance with atleast one aspect of the present disclosure.

FIG. 26 is a graphical display of an impedance analyzer showingimpedance/admittance circle plots for an ultrasonic device with the jawclamped on dry chamois where complex admittance is depicted in brokenline and complex impedance is depicted in solid line, in accordance withat least one aspect of the present disclosure.

FIG. 27 is a graphical display of an impedance analyzer showingimpedance/admittance circle plots for an ultrasonic device with the jawtip clamped on moist chamois where complex admittance is depicted inbroken line and complex impedance is depicted in solid line, inaccordance with at least one aspect of the present disclosure.

FIG. 28 is a graphical display of an impedance analyzer showingimpedance/admittance circle plots for an ultrasonic device with the jawfully clamped on moist chamois where complex admittance is depicted inbroken line and complex impedance is depicted in solid line, inaccordance with at least one aspect of the present disclosure.

FIG. 29 is a graphical display of an impedance analyzer showingimpedance/admittance plots where frequency is swept from 48 kHz to 62kHz to capture multiple resonances of an ultrasonic device with the jawopen where the rectangular overlay shown in broken line is to help seethe circles, in accordance with at least one aspect of the presentdisclosure.

FIG. 30 is a logic flow diagram of a process depicting a control programor a logic configuration to determine jaw conditions based on estimatesof the radius and offsets of an impedance/admittance circle, inaccordance with at least one aspect of the present disclosure.

FIG. 31 is a three-dimensional graphical representation of tissue radiofrequency (RF) impedance classification, in accordance with at least oneaspect of the present disclosure.

FIG. 32 is a three-dimensional graphical representation of tissue radiofrequency (RF) impedance analysis, in accordance with at least oneaspect of the present disclosure.

DESCRIPTION

Applicant of the present patent application also owns the followingcontemporaneously-filed U.S. patent applications, each of which isherein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application titled METHODS FOR        CONTROLLING TEMPERATURE IN ULTRASONIC DEVICE, Attorney Docket        No. END8560USNP1/180106-1M;    -   U.S. Provisional Patent Application titled ULTRASONIC SEALING        ALGORITHM WITH TEMPERATURE CONTROL, Attorney Docket No.        END8560USNP3/180106-3;    -   U.S. Provisional Patent Application titled APPLICATION OF SMART        ULTRASONIC BLADE TECHNOLOGY, Attorney Docket No.        END8560USNP4/180106-4;    -   U.S. Provisional Patent Application titled ADAPTIVE ADVANCED        TISSUE TREATMENT PAD SAVER MODE, Attorney Docket No.        END8560USNP5/180106-5;    -   U.S. Provisional Patent Application titled SMART BLADE        TECHNOLOGY TO CONTROL BLADE INSTABILITY, Attorney Docket No.        END8560USNP6/180106-6; and    -   U.S. Provisional Patent Application titled START TEMPERATURE OF        BLADE, Attorney Docket No. END8560USNP7/180106-7.

Applicant of the present patent application also owns the followingcontemporaneously-filed U.S. patent applications, each of which isherein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application titled METHODS FOR        ESTIMATING AND CONTROLLING STATE OF ULTRASONIC END EFFECTOR,        Attorney Docket No. END8536USNP1/180107-1M;    -   U.S. Provisional Patent Application titled IN-THE-JAW CLASSIFIER        BASED ON MODEL, Attorney Docket No. END8536USNP3/180107-3;    -   U.S. Provisional Patent Application titled APPLICATION OF SMART        BLADE TECHNOLOGY, Attorney Docket No. END8536USNP4/180107-4;    -   U.S. Provisional Patent Application titled SMART BLADE AND POWER        PULSING, Attorney Docket No. END8536USNP5/180107-5;    -   U.S. Provisional Patent Application titled ADJUSTMENT OF COMPLEX        IMPEDANCE TO COMPENSATE FOR LOST POWER IN AN ARTICULATING        ULTRASONIC DEVICE, Attorney Docket No. END8536USNP6/180107-6;    -   U.S. Provisional Patent Application titled USING SPECTROSCOPY TO        DETERMINE DEVICE USE STATE IN COMBO INSTRUMENT, Attorney Docket        No. END8536USNP7/180107-7;    -   U.S. Provisional Patent Application titled VESSEL SENSING FOR        ADAPTIVE ADVANCED HEMOSTASIS, Attorney Docket No.        END8536USNP8/180107-8;    -   U.S. Provisional Patent Application titled CALCIFIED VESSEL        IDENTIFICATION, Attorney Docket No. END8536USNP9/180107-9;    -   U.S. Provisional Patent Application titled DETECTION OF LARGE        VESSELS DURING PARENCHYMAL DISSECTION USING A SMART BLADE,        Attorney Docket No. END8536USNP10/180107-10;    -   U.S. Provisional Patent Application titled SMART BLADE        APPLICATION FOR REUSABLE AND DISPOSABLE DEVICES, Attorney Docket        No. END8536USNP11/180107-11; and    -   U.S. Provisional Patent Application titled FINE DISSECTION MODE        FOR TISSUE CLASSIFICATION, Attorney Docket No.        END8536USNP13/180107-13.

Applicant of the present application owns the following U.S. PatentApplications, filed on Sep. 10, 2018, the disclosure of each of which isherein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application Ser. No. 62/729,177, titled        AUTOMATED DATA SCALING, ALIGNMENT, AND ORGANIZING BASED ON        PREDEFINED PARAMETERS WITHIN A SURGICAL NETWORK BEFORE        TRANSMISSION;    -   U.S. provisional Patent Application Ser. No. 62/729,182, titled        SENSING THE PATIENT POSITION AND CONTACT UTILIZING THE        MONO-POLAR RETURN PAD ELECTRODE TO PROVIDE SITUATIONAL AWARENESS        TO THE HUB;    -   U.S. Provisional Patent Application Ser. No. 62/729,184, titled        POWERED SURGICAL TOOL WITH A PREDEFINED ADJUSTABLE CONTROL        ALGORITHM FOR CONTROLLING AT LEAST ONE END-EFFECTOR PARAMETER        AND A MEANS FOR LIMITING THE ADJUSTMENT;    -   U.S. Provisional Patent Application Ser. No. 62/729,183, titled        SURGICAL NETWORK RECOMMENDATIONS FROM REAL TIME ANALYSIS OF        PROCEDURE VARIABLES AGAINST A BASELINE HIGHLIGHTING DIFFERENCES        FROM THE OPTIMAL SOLUTION;    -   U.S. Provisional Patent Application Ser. No. 62/729,191, titled        A CONTROL FOR A SURGICAL NETWORK OR SURGICAL NETWORK CONNECTED        DEVICE THAT ADJUSTS ITS FUNCTION BASED ON A SENSED SITUATION OR        USAGE;    -   U.S. Provisional Patent Application Ser. No. 62/729,176, titled        INDIRECT COMMAND AND CONTROL OF A FIRST OPERATING ROOM SYSTEM        THROUGH THE USE OF A SECOND OPERATING ROOM SYSTEM WITHIN A        STERILE FIELD WHERE THE SECOND OPERATING ROOM SYSTEM HAS PRIMARY        AND SECONDARY OPERATING MODES;    -   U.S. Provisional Patent Application Ser. No. 62/729,186, titled        WIRELESS PAIRING OF A SURGICAL DEVICE WITH ANOTHER DEVICE WITHIN        A STERILE SURGICAL FIELD BASED ON THE USAGE AND SITUATIONAL        AWARENESS OF DEVICES; and    -   U.S. Provisional Patent Application Ser. No. 62/729,185, titled        POWERED STAPLING DEVICE THAT IS CAPABLE OF ADJUSTING FORCE,        ADVANCEMENT SPEED, AND OVERALL STROKE OF CUTTING MEMBER OF THE        DEVICE BASED ON SENSED PARAMETER OF FIRING OR CLAMPING.

Applicant of the present application owns the following U.S. PatentApplications, filed on Aug. 28, 2018, the disclosure of each of which isherein incorporated by reference in its entirety:

-   -   U.S. patent application Ser. No. 16/115,214, titled ESTIMATING        STATE OF ULTRASONIC END EFFECTOR AND CONTROL SYSTEM THEREFOR;    -   U.S. patent application Ser. No. 16/115,205, titled TEMPERATURE        CONTROL OF ULTRASONIC END EFFECTOR AND CONTROL SYSTEM THEREFOR;    -   U.S. patent application Ser. No. 16/115,233, titled RADIO        FREQUENCY ENERGY DEVICE FOR DELIVERING COMBINED ELECTRICAL        SIGNALS;    -   U.S. patent application Ser. No. 16/115,208, titled CONTROLLING        AN ULTRASONIC SURGICAL INSTRUMENT ACCORDING TO TISSUE LOCATION;    -   U.S. patent application Ser. No. 16/115,220, titled CONTROLLING        ACTIVATION OF AN ULTRASONIC SURGICAL INSTRUMENT ACCORDING TO THE        PRESENCE OF TISSUE;    -   U.S. patent application Ser. No. 16/115,232, titled DETERMINING        TISSUE COMPOSITION VIA AN ULTRASONIC SYSTEM;    -   U.S. patent application Ser. No. 16/115,239, titled DETERMINING        THE STATE OF AN ULTRASONIC ELECTROMECHANICAL SYSTEM ACCORDING TO        FREQUENCY SHIFT;    -   U.S. patent application Ser. No. 16/115,247, titled DETERMINING        THE STATE OF AN ULTRASONIC END EFFECTOR;    -   U.S. patent application Ser. No. 16/115,211, titled SITUATIONAL        AWARENESS OF ELECTROSURGICAL SYSTEMS;    -   U.S. patent application Ser. No. 16/115,226, titled MECHANISMS        FOR CONTROLLING DIFFERENT ELECTROMECHANICAL SYSTEMS OF AN        ELECTROSURGICAL INSTRUMENT;    -   U.S. patent application Ser. No. 16/115,240, titled DETECTION OF        END EFFECTOR EMERSION IN LIQUID;    -   U.S. patent application Ser. No. 16/115,249, titled INTERRUPTION        OF ENERGY DUE TO INADVERTENT CAPACITIVE COUPLING;    -   U.S. patent application Ser. No. 16/115,256, titled INCREASING        RADIO FREQUENCY TO CREATE PAD-LESS MONOPOLAR LOOP;    -   U.S. patent application Ser. No. 16/115,223, titled BIPOLAR        COMBINATION DEVICE THAT AUTOMATICALLY ADJUSTS PRESSURE BASED ON        ENERGY MODALITY; and    -   U.S. patent application Ser. No. 16/115,238, titled ACTIVATION        OF ENERGY DEVICES.

Applicant of the present application owns the following U.S. PatentApplications, filed on Aug. 23, 2018, the disclosure of each of which isherein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application No. 62/721,995, titled        CONTROLLING AN ULTRASONIC SURGICAL INSTRUMENT ACCORDING TO        TISSUE LOCATION;    -   U.S. Provisional Patent Application No. 62/721,998, titled        SITUATIONAL AWARENESS OF ELECTROSURGICAL SYSTEMS;    -   U.S. Provisional Patent Application No. 62/721,999, titled        INTERRUPTION OF ENERGY DUE TO INADVERTENT CAPACITIVE COUPLING;    -   U.S. Provisional Patent Application No. 62/721,994, titled        BIPOLAR COMBINATION DEVICE THAT AUTOMATICALLY ADJUSTS PRESSURE        BASED ON ENERGY MODALITY; and    -   U.S. Provisional Patent Application No. 62/721,996, titled RADIO        FREQUENCY ENERGY DEVICE FOR DELIVERING COMBINED ELECTRICAL        SIGNALS.

Applicant of the present application owns the following U.S. PatentApplications, filed on Jun. 30, 2018, the disclosure of each of which isherein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application No. 62/692,747, titled SMART        ACTIVATION OF AN ENERGY DEVICE BY ANOTHER DEVICE;    -   U.S. Provisional Patent Application No. 62/692,748, titled SMART        ENERGY ARCHITECTURE; and    -   U.S. Provisional Patent Application No. 62/692,768, titled SMART        ENERGY DEVICES.

Applicant of the present application owns the following U.S. PatentApplications, filed on Jun. 29, 2018, the disclosure of each of which isherein incorporated by reference in its entirety:

-   -   U.S. patent application Ser. No. 16/024,090, titled CAPACITIVE        COUPLED RETURN PATH PAD WITH SEPARABLE ARRAY ELEMENTS;    -   U.S. patent application Ser. No. 16/024,057, titled CONTROLLING        A SURGICAL INSTRUMENT ACCORDING TO SENSED CLOSURE PARAMETERS;    -   U.S. patent application Ser. No. 16/024,067, titled SYSTEMS FOR        ADJUSTING END EFFECTOR PARAMETERS BASED ON PERIOPERATIVE        INFORMATION;    -   U.S. patent application Ser. No. 16/024,075, titled SAFETY        SYSTEMS FOR SMART POWERED SURGICAL STAPLING;    -   U.S. patent application Ser. No. 16/024,083, titled SAFETY        SYSTEMS FOR SMART POWERED SURGICAL STAPLING;    -   U.S. patent application Ser. No. 16/024,094, titled SURGICAL        SYSTEMS FOR DETECTING END EFFECTOR TISSUE DISTRIBUTION        IRREGULARITIES;    -   U.S. patent application Ser. No. 16/024,138, titled SYSTEMS FOR        DETECTING PROXIMITY OF SURGICAL END EFFECTOR TO CANCEROUS        TISSUE;    -   U.S. patent application Ser. No. 16/024,150, titled SURGICAL        INSTRUMENT CARTRIDGE SENSOR ASSEMBLIES;    -   U.S. patent application Ser. No. 16/024,160, titled VARIABLE        OUTPUT CARTRIDGE SENSOR ASSEMBLY;    -   U.S. patent application Ser. No. 16/024,124, titled SURGICAL        INSTRUMENT HAVING A FLEXIBLE ELECTRODE;    -   U.S. patent application Ser. No. 16/024,132, titled SURGICAL        INSTRUMENT HAVING A FLEXIBLE CIRCUIT;    -   U.S. patent application Ser. No. 16/024,141, titled SURGICAL        INSTRUMENT WITH A TISSUE MARKING ASSEMBLY;    -   U.S. patent application Ser. No. 16/024,162, titled SURGICAL        SYSTEMS WITH PRIORITIZED DATA TRANSMISSION CAPABILITIES;    -   U.S. patent application Ser. No. 16/024,066, titled SURGICAL        EVACUATION SENSING AND MOTOR CONTROL;    -   U.S. patent application Ser. No. 16/024,096, titled SURGICAL        EVACUATION SENSOR ARRANGEMENTS;    -   U.S. patent application Ser. No. 16/024,116, titled SURGICAL        EVACUATION FLOW PATHS;    -   U.S. patent application Ser. No. 16/024,149, titled SURGICAL        EVACUATION SENSING AND GENERATOR CONTROL;    -   U.S. patent application Ser. No. 16/024,180, titled SURGICAL        EVACUATION SENSING AND DISPLAY;    -   U.S. patent application Ser. No. 16/024,245, titled        COMMUNICATION OF SMOKE EVACUATION SYSTEM PARAMETERS TO HUB OR        CLOUD IN SMOKE EVACUATION MODULE FOR INTERACTIVE SURGICAL        PLATFORM;    -   U.S. patent application Ser. No. 16/024,258, titled SMOKE        EVACUATION SYSTEM INCLUDING A SEGMENTED CONTROL CIRCUIT FOR        INTERACTIVE SURGICAL PLATFORM;    -   U.S. patent application Ser. No. 16/024,265, titled SURGICAL        EVACUATION SYSTEM WITH A COMMUNICATION CIRCUIT FOR COMMUNICATION        BETWEEN A FILTER AND A SMOKE EVACUATION DEVICE; and    -   U.S. patent application Ser. No. 16/024,273, titled DUAL        IN-SERIES LARGE AND SMALL DROPLET FILTERS.

Applicant of the present application owns the following U.S. ProvisionalPatent Applications, filed on Jun. 28, 2018, the disclosure of each ofwhich is herein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application Ser. No. 62/691,228, titled        A METHOD OF USING REINFORCED FLEX CIRCUITS WITH MULTIPLE SENSORS        WITH ELECTROSURGICAL DEVICES;    -   U.S. Provisional Patent Application Ser. No. 62/691,227, titled        CONTROLLING A SURGICAL INSTRUMENT ACCORDING TO SENSED CLOSURE        PARAMETERS;    -   U.S. Provisional Patent Application Ser. No. 62/691,230, titled        SURGICAL INSTRUMENT HAVING A FLEXIBLE ELECTRODE;    -   U.S. Provisional Patent Application Ser. No. 62/691,219, titled        SURGICAL EVACUATION SENSING AND MOTOR CONTROL;    -   U.S. Provisional Patent Application Ser. No. 62/691,257, titled        COMMUNICATION OF SMOKE EVACUATION SYSTEM PARAMETERS TO HUB OR        CLOUD IN SMOKE EVACUATION MODULE FOR INTERACTIVE SURGICAL        PLATFORM;    -   U.S. Provisional Patent Application Ser. No. 62/691,262, titled        SURGICAL EVACUATION SYSTEM WITH A COMMUNICATION CIRCUIT FOR        COMMUNICATION BETWEEN A FILTER AND A SMOKE EVACUATION DEVICE;        and    -   U.S. Provisional Patent Application Ser. No. 62/691,251, titled        DUAL IN-SERIES LARGE AND SMALL DROPLET FILTERS.

Applicant of the present application owns the following U.S. ProvisionalPatent Application, filed on Apr. 19, 2018, the disclosure of each ofwhich is herein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application Ser. No. 62/659,900, titled        METHOD OF HUB COMMUNICATION.

Applicant of the present application owns the following U.S. ProvisionalPatent Applications, filed on Mar. 30, 2018, the disclosure of each ofwhich is herein incorporated by reference in its entirety:

-   -   U. S. Provisional Patent Application No. 62/650,898 filed on        Mar. 30, 2018, titled CAPACITIVE COUPLED RETURN PATH PAD WITH        SEPARABLE ARRAY ELEMENTS;    -   U.S. Provisional Patent Application Ser. No. 62/650,887, titled        SURGICAL SYSTEMS WITH OPTIMIZED SENSING CAPABILITIES;    -   U.S. Provisional Patent Application Ser. No. 62/650,882, titled        SMOKE EVACUATION MODULE FOR INTERACTIVE SURGICAL PLATFORM; and    -   U.S. Provisional Patent Application Ser. No. 62/650,877, titled        SURGICAL SMOKE EVACUATION SENSING AND CONTROLS.

Applicant of the present application owns the following U.S. PatentApplications, filed on Mar. 29, 2018, the disclosure of each of which isherein incorporated by reference in its entirety:

-   -   U.S. patent application Ser. No. 15/940,641, titled INTERACTIVE        SURGICAL SYSTEMS WITH ENCRYPTED COMMUNICATION CAPABILITIES;    -   U.S. patent application Ser. No. 15/940,648, titled INTERACTIVE        SURGICAL SYSTEMS WITH CONDITION HANDLING OF DEVICES AND DATA        CAPABILITIES;    -   U.S. patent application Ser. No. 15/940,656, titled SURGICAL HUB        COORDINATION OF CONTROL AND COMMUNICATION OF OPERATING ROOM        DEVICES;    -   U.S. patent application Ser. No. 15/940,666, titled SPATIAL        AWARENESS OF SURGICAL HUBS IN OPERATING ROOMS;    -   U.S. patent application Ser. No. 15/940,670, titled COOPERATIVE        UTILIZATION OF DATA DERIVED FROM SECONDARY SOURCES BY        INTELLIGENT SURGICAL HUBS;    -   U.S. patent application Ser. No. 15/940,677, titled SURGICAL HUB        CONTROL ARRANGEMENTS;    -   U.S. patent application Ser. No. 15/940,632, titled DATA        STRIPPING METHOD TO INTERROGATE PATIENT RECORDS AND CREATE        ANONYMIZED RECORD;    -   U.S. patent application Ser. No. 15/940,640, titled        COMMUNICATION HUB AND STORAGE DEVICE FOR STORING PARAMETERS AND        STATUS OF A SURGICAL DEVICE TO BE SHARED WITH CLOUD BASED        ANALYTICS SYSTEMS;    -   U.S. patent application Ser. No. 15/940,645, titled SELF        DESCRIBING DATA PACKETS GENERATED AT AN ISSUING INSTRUMENT;    -   U.S. patent application Ser. No. 15/940,649, titled DATA PAIRING        TO INTERCONNECT A DEVICE MEASURED PARAMETER WITH AN OUTCOME;    -   U.S. patent application Ser. No. 15/940,654, titled SURGICAL HUB        SITUATIONAL AWARENESS;    -   U.S. patent application Ser. No. 15/940,663, titled SURGICAL        SYSTEM DISTRIBUTED PROCESSING;    -   U.S. patent application Ser. No. 15/940,668, titled AGGREGATION        AND REPORTING OF SURGICAL HUB DATA;    -   U.S. patent application Ser. No. 15/940,671, titled SURGICAL HUB        SPATIAL AWARENESS TO DETERMINE DEVICES IN OPERATING THEATER;    -   U.S. patent application Ser. No. 15/940,686, titled DISPLAY OF        ALIGNMENT OF STAPLE CARTRIDGE TO PRIOR LINEAR STAPLE LINE;    -   U.S. patent application Ser. No. 15/940,700, titled STERILE        FIELD INTERACTIVE CONTROL DISPLAYS;    -   U.S. patent application Ser. No. 15/940,629, titled COMPUTER        IMPLEMENTED INTERACTIVE SURGICAL SYSTEMS;    -   U.S. patent application Ser. No. 15/940,704, titled USE OF LASER        LIGHT AND RED-GREEN-BLUE COLORATION TO DETERMINE PROPERTIES OF        BACK SCATTERED LIGHT;    -   U.S. patent application Ser. No. 15/940,722, titled        CHARACTERIZATION OF TISSUE IRREGULARITIES THROUGH THE USE OF        MONO-CHROMATIC LIGHT REFRACTIVITY; and    -   U.S. patent application Ser. No. 15/940,742, titled DUAL CMOS        ARRAY IMAGING.    -   U.S. patent application Ser. No. 15/940,636, titled ADAPTIVE        CONTROL PROGRAM UPDATES FOR SURGICAL DEVICES;    -   U.S. patent application Ser. No. 15/940,653, titled ADAPTIVE        CONTROL PROGRAM UPDATES FOR SURGICAL HUBS;    -   U.S. patent application Ser. No. 15/940,660, titled CLOUD-BASED        MEDICAL ANALYTICS FOR CUSTOMIZATION AND RECOMMENDATIONS TO A        USER;    -   U.S. patent application Ser. No. 15/940,679, titled CLOUD-BASED        MEDICAL ANALYTICS FOR LINKING OF LOCAL USAGE TRENDS WITH THE        RESOURCE ACQUISITION BEHAVIORS OF LARGER DATA SET;    -   U.S. patent application Ser. No. 15/940,694, titled CLOUD-BASED        MEDICAL ANALYTICS FOR MEDICAL FACILITY SEGMENTED        INDIVIDUALIZATION OF INSTRUMENT FUNCTION;    -   U.S. patent application Ser. No. 15/940,634, titled CLOUD-BASED        MEDICAL ANALYTICS FOR SECURITY AND AUTHENTICATION TRENDS AND        REACTIVE MEASURES;    -   U.S. patent application Ser. No. 15/940,706, titled DATA        HANDLING AND PRIORITIZATION IN A CLOUD ANALYTICS NETWORK; and    -   U.S. patent application Ser. No. 15/940,675, titled CLOUD        INTERFACE FOR COUPLED SURGICAL DEVICES.    -   U.S. patent application Ser. No. 15/940,627, titled DRIVE        ARRANGEMENTS FOR ROBOT-ASSISTED SURGICAL PLATFORMS;    -   U.S. patent application Ser. No. 15/940,637, titled        COMMUNICATION ARRANGEMENTS FOR ROBOT-ASSISTED SURGICAL        PLATFORMS;    -   U.S. patent application Ser. No. 15/940,642, titled CONTROLS FOR        ROBOT-ASSISTED SURGICAL PLATFORMS;    -   U.S. patent application Ser. No. 15/940,676, titled AUTOMATIC        TOOL ADJUSTMENTS FOR ROBOT-ASSISTED SURGICAL PLATFORMS;    -   U.S. patent application Ser. No. 15/940,680, titled CONTROLLERS        FOR ROBOT-ASSISTED SURGICAL PLATFORMS;    -   U.S. patent application Ser. No. 15/940,683, titled COOPERATIVE        SURGICAL ACTIONS FOR ROBOT-ASSISTED SURGICAL PLATFORMS;    -   U.S. patent application Ser. No. 15/940,690, titled DISPLAY        ARRANGEMENTS FOR ROBOT-ASSISTED SURGICAL PLATFORMS; and    -   U.S. patent application Ser. No. 15/940,711, titled SENSING        ARRANGEMENTS FOR ROBOT-ASSISTED SURGICAL PLATFORMS.

Applicant of the present application owns the following U.S. ProvisionalPatent Applications, filed on Mar. 28, 2018, the disclosure of each ofwhich is herein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application Ser. No. 62/649,302, titled        INTERACTIVE SURGICAL SYSTEMS WITH ENCRYPTED COMMUNICATION        CAPABILITIES;    -   U.S. Provisional Patent Application Ser. No. 62/649,294, titled        DATA STRIPPING METHOD TO INTERROGATE PATIENT RECORDS AND CREATE        ANONYMIZED RECORD;    -   U.S. Provisional Patent Application Ser. No. 62/649,300, titled        SURGICAL HUB SITUATIONAL AWARENESS;    -   U.S. Provisional Patent Application Ser. No. 62/649,309, titled        SURGICAL HUB SPATIAL AWARENESS TO DETERMINE DEVICES IN OPERATING        THEATER;    -   U.S. Provisional Patent Application Ser. No. 62/649,310, titled        COMPUTER IMPLEMENTED INTERACTIVE SURGICAL SYSTEMS;    -   U.S. Provisional Patent Application Ser. No. 62/649,291, titled        USE OF LASER LIGHT AND RED-GREEN-BLUE COLORATION TO DETERMINE        PROPERTIES OF BACK SCATTERED LIGHT;    -   U.S. Provisional Patent Application Ser. No. 62/649,296, titled        ADAPTIVE CONTROL PROGRAM UPDATES FOR SURGICAL DEVICES;    -   U.S. Provisional Patent Application Ser. No. 62/649,333, titled        CLOUD-BASED MEDICAL ANALYTICS FOR CUSTOMIZATION AND        RECOMMENDATIONS TO A USER;    -   U.S. Provisional Patent Application Ser. No. 62/649,327, titled        CLOUD-BASED MEDICAL ANALYTICS FOR SECURITY AND AUTHENTICATION        TRENDS AND REACTIVE MEASURES;    -   U.S. Provisional Patent Application Ser. No. 62/649,315, titled        DATA HANDLING AND PRIORITIZATION IN A CLOUD ANALYTICS NETWORK;    -   U.S. Provisional Patent Application Ser. No. 62/649,313, titled        CLOUD INTERFACE FOR COUPLED SURGICAL DEVICES;    -   U.S. Provisional Patent Application Ser. No. 62/649,320, titled        DRIVE ARRANGEMENTS FOR ROBOT-ASSISTED SURGICAL PLATFORMS;    -   U.S. Provisional Patent Application Ser. No. 62/649,307, titled        AUTOMATIC TOOL ADJUSTMENTS FOR ROBOT-ASSISTED SURGICAL        PLATFORMS; and    -   U.S. Provisional Patent Application Ser. No. 62/649,323, titled        SENSING ARRANGEMENTS FOR ROBOT-ASSISTED SURGICAL PLATFORMS.

Applicant of the present application owns the following U.S. ProvisionalPatent Applications, filed on Dec. 28, 2017, the disclosure of each ofwhich is herein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application Ser. No. U.S. Provisional        Patent Application Ser. No. 62/611,341, titled INTERACTIVE        SURGICAL PLATFORM;    -   U.S. Provisional Patent Application Ser. No. 62/611,340, titled        CLOUD-BASED MEDICAL ANALYTICS; and    -   U.S. Provisional Patent Application Ser. No. 62/611,339, titled        ROBOT ASSISTED SURGICAL PLATFORM.

Before explaining various aspects of surgical devices and generators indetail, it should be noted that the illustrative examples are notlimited in application or use to the details of construction andarrangement of parts illustrated in the accompanying drawings anddescription. The illustrative examples may be implemented orincorporated in other aspects, variations and modifications, and may bepracticed or carried out in various ways. Further, unless otherwiseindicated, the terms and expressions employed herein have been chosenfor the purpose of describing the illustrative examples for theconvenience of the reader and are not for the purpose of limitationthereof. Also, it will be appreciated that one or more of thefollowing-described aspects, expressions of aspects, and/or examples,can be combined with any one or more of the other following-describedaspects, expressions of aspects and/or examples.

Various aspects are directed to improved ultrasonic surgical devices,electrosurgical devices and generators for use therewith. Aspects of theultrasonic surgical devices can be configured for transecting and/orcoagulating tissue during surgical procedures, for example. Aspects ofthe electrosurgical devices can be configured for transecting,coagulating, scaling, welding and/or desiccating tissue during surgicalprocedures, for example.

Adaptive Ultrasonic Blade Control Algorithms

In various aspects smart ultrasonic energy devices may comprise adaptivealgorithms to control the operation of the ultrasonic blade. In oneaspect, the ultrasonic blade adaptive control algorithms are configuredto identify tissue type and adjust device parameters. In one aspect, theultrasonic blade control algorithms are configured to parameterizetissue type. An algorithm to detect the collagen/elastic ratio of tissueto tune the amplitude of the distal tip of the ultrasonic blade isdescribed in the following section of the present disclosure. Variousaspects of smart ultrasonic energy devices are described herein inconnection with FIGS. 1-2, for example. Accordingly, the followingdescription of adaptive ultrasonic blade control algorithms should beread in conjunction with FIGS. 1-2 and the description associatedtherewith.

In certain surgical procedures it would be desirable to employ adaptiveultrasonic blade control algorithms. In one aspect, adaptive ultrasonicblade control algorithms may be employed to adjust the parameters of theultrasonic device based on the type of tissue in contact with theultrasonic blade. In one aspect, the parameters of the ultrasonic devicemay be adjusted based on the location of the tissue within the jaws ofthe ultrasonic end effector, for example, the location of the tissuebetween the clamp arm and the ultrasonic blade. The impedance of theultrasonic transducer may be employed to differentiate what percentageof the tissue is located in the distal or proximal end of the endeffector. The reactions of the ultrasonic device may be based on thetissue type or compressibility of the tissue. In another aspect, theparameters of the ultrasonic device may be adjusted based on theidentified tissue type or parameterization. For example, the mechanicaldisplacement amplitude of the distal tip of the ultrasonic blade may betuned based on the ration of collagen to elastin tissue detected duringthe tissue identification procedure. The ratio of collagen to elastintissue may be detected used a variety of techniques including infrared(IR) surface reflectance and emissivity. The force applied to the tissueby the clamp arm and/or the stroke of the clamp arm to produce gap andcompression. Electrical continuity across a jaw equipped with electrodesmay be employed to determine what percentage of the jaw is covered withtissue.

FIG. 1 is a system 800 configured to execute adaptive ultrasonic bladecontrol algorithms in a surgical data network comprising a modularcommunication hub, in accordance with at least one aspect of the presentdisclosure. In one aspect, the generator module 240 is configured toexecute the adaptive ultrasonic blade control algorithm(s) 802 asdescribed herein. In another aspect, the device/instrument 235 isconfigured to execute the adaptive ultrasonic blade control algorithm(s)804 as described herein with reference to FIGS. 19-32. In anotheraspect, both the device/instrument 235 and the device/instrument 235 areconfigured to execute the adaptive ultrasonic blade control algorithms802, 804 as described herein with reference to FIGS. 19-32.

The generator module 240 may comprise a patient isolated stage incommunication with a non-isolated stage via a power transformer. Asecondary winding of the power transformer is contained in the isolatedstage and may comprise a tapped configuration (e.g., a center-tapped ora non-center-tapped configuration) to define drive signal outputs fordelivering drive signals to different surgical instruments, such as, forexample, an ultrasonic surgical instrument, an RF electrosurgicalinstrument, and a multifunction surgical instrument which includesultrasonic and RF energy modes that can be delivered alone orsimultaneously. In particular, the drive signal outputs may output anultrasonic drive signal (e.g., a 420V root-mean-square (RMS) drivesignal) to an ultrasonic surgical instrument 241, and the drive signaloutputs may output an RF electrosurgical drive signal (e.g., a 100V RMSdrive signal) to an RF electrosurgical instrument 241. Aspects of thegenerator module 240 are described herein with reference to FIGS. 7-12.

The generator module 240 or the device/instrument 235 or both arecoupled to the modular control tower 236 connected to multiple operatingtheater devices such as, for example, intelligent surgical instruments,robots, and other computerized devices located in the operating theater.In some aspects, a surgical data network may include a modularcommunication hub configured to connect modular devices located in oneor more operating theaters of a healthcare facility, or any room in ahealthcare facility specially equipped for surgical operations, to acloud-based system (e.g., the cloud 204 that may include a remote server213 coupled to a storage device).

Modular devices located in the operating theater may be coupled to themodular communication hub. The network hub and/or the network switch maybe coupled to a network router to connect the devices to the cloud 204or a local computer system. Data associated with the devices may betransferred to cloud-based computers via the router for remote dataprocessing and manipulation. Data associated with the devices may alsobe transferred to a local computer system for local data processing andmanipulation. Modular devices located in the same operating theater alsomay be coupled to a network switch. The network switch may be coupled tothe network hub and/or the network router to connect to the devices tothe cloud 204. Data associated with the devices may be transferred tothe cloud 204 via the network router for data processing andmanipulation. Data associated with the devices may also be transferredto the local computer system for local data processing and manipulation.

It will be appreciated that cloud computing relies on sharing computingresources rather than having local servers or personal devices to handlesoftware applications. The word “cloud” may be used as a metaphor for“the Internet,” although the term is not limited as such. Accordingly,the term “cloud computing” may be used herein to refer to “a type ofInternet-based computing,” where different services—such as servers,storage, and applications—are delivered to the modular communication huband/or computer system located in the surgical theater (e.g., a fixed,mobile, temporary, or field operating room or space) and to devicesconnected to the modular communication hub and/or computer systemthrough the Internet. The cloud infrastructure may be maintained by acloud service provider. In this context, the cloud service provider maybe the entity that coordinates the usage and control of the deviceslocated in one or more operating theaters. The cloud computing servicescan perform a large number of calculations based on the data gathered bysmart surgical instruments, robots, and other computerized deviceslocated in the operating theater. The hub hardware enables multipledevices or connections to be connected to a computer that communicateswith the cloud computing resources and storage.

FIG. 1 further illustrates some aspects of a computer-implementedinteractive surgical system comprising a modular communication hub thatmay include the system 800 configured to execute adaptive ultrasonicblade control algorithms in a surgical data network. The surgical systemmay include at least one surgical hub in communication with a cloud 204that may include a remote server 213. In one aspect, thecomputer-implemented interactive surgical system comprises a modularcontrol tower 236 connected to multiple operating theater devices suchas, for example, intelligent surgical instruments, robots, and othercomputerized devices located in the operating theater. The modularcontrol tower 236 may comprise a modular communication hub coupled to acomputer system. In some aspects, the modular control tower 236 iscoupled to an imaging module that is coupled to an endoscope, agenerator module 240 that is coupled to an energy device 241, and asmart device/instrument 235 optionally coupled to a display 237. Theoperating theater devices are coupled to cloud computing resources anddata storage via the modular control tower 236. A robot hub 222 also maybe connected to the modular control tower 236 and to the cloud computingresources. The devices/instruments 235, visualization systems 208, amongothers, may be coupled to the modular control tower 236 via wired orwireless communication standards or protocols, as described herein. Themodular control tower 236 may be coupled to a hub display 215 (e.g.,monitor, screen) to display and overlay images received from the imagingmodule, device/instrument display, and/or other visualization systems208. The hub display 215 also may display data received from devicesconnected to the modular control tower in conjunction with images andoverlaid images.

Generator Hardware

FIG. 2 illustrates an example of a generator 900, which is one form of agenerator configured to couple to an ultrasonic instrument and furtherconfigured to execute adaptive ultrasonic blade control algorithms in asurgical data network comprising a modular communication hub as shown inFIG. 1. The generator 900 is configured to deliver multiple energymodalities to a surgical instrument. The generator 900 provides RF andultrasonic signals for delivering energy to a surgical instrument eitherindependently or simultaneously. The RF and ultrasonic signals may beprovided alone or in combination and may be provided simultaneously. Asnoted above, at least one generator output can deliver multiple energymodalities (e.g., ultrasonic, bipolar or monopolar RF, irreversibleand/or reversible electroporation, and/or microwave energy, amongothers) through a single port, and these signals can be deliveredseparately or simultaneously to the end effector to treat tissue. Thegenerator 900 comprises a processor 902 coupled to a waveform generator904. The processor 902 and waveform generator 904 are configured togenerate a variety of signal waveforms based on information stored in amemory coupled to the processor 902, not shown for clarity ofdisclosure. The digital information associated with a waveform isprovided to the waveform generator 904 which includes one or more DACcircuits to convert the digital input into an analog output. The analogoutput is fed to an amplifier 906 for signal conditioning andamplification. The conditioned and amplified output of the amplifier 906is coupled to a power transformer 908. The signals are coupled acrossthe power transformer 908 to the secondary side, which is in the patientisolation side. A first signal of a first energy modality is provided tothe surgical instrument between the terminals labeled ENERGY₁ andRETURN. A second signal of a second energy modality is coupled across acapacitor 910 and is provided to the surgical instrument between theterminals labeled ENERGY₂ and RETURN. It will be appreciated that morethan two energy modalities may be output and thus the subscript “n” maybe used to designate that up to n ENERGY_(n) terminals may be provided,where n is a positive integer greater than 1. It also will beappreciated that up to “n” return paths RETURN_(n) may be providedwithout departing from the scope of the present disclosure.

A first voltage sensing circuit 912 is coupled across the terminalslabeled ENERGY₁ and the RETURN path to measure the output voltagetherebetween. A second voltage sensing circuit 924 is coupled across theterminals labeled ENERGY₂ and the RETURN path to measure the outputvoltage therebetween. A current sensing circuit 914 is disposed inseries with the RETURN leg of the secondary side of the powertransformer 908 as shown to measure the output current for either energymodality. If different return paths are provided for each energymodality, then a separate current sensing circuit should be provided ineach return leg. The outputs of the first and second voltage sensingcircuits 912, 924 are provided to respective isolation transformers 916,922 and the output of the current sensing circuit 914 is provided toanother isolation transformer 918. The outputs of the isolationtransformers 916, 928, 922 in the on the primary side of the powertransformer 908 (non-patient isolated side) are provided to a one ormore ADC circuit 926. The digitized output of the ADC circuit 926 isprovided to the processor 902 for further processing and computation.The output voltages and output current feedback information can beemployed to adjust the output voltage and current provided to thesurgical instrument and to compute output impedance, among otherparameters. Input/output communications between the processor 902 andpatient isolated circuits is provided through an interface circuit 920.Sensors also may be in electrical communication with the processor 902by way of the interface circuit 920.

In one aspect, the impedance may be determined by the processor 902 bydividing the output of either the first voltage sensing circuit 912coupled across the terminals labeled ENERGY₁/RETURN or the secondvoltage sensing circuit 924 coupled across the terminals labeledENERGY₂/RETURN by the output of the current sensing circuit 914 disposedin series with the RETURN leg of the secondary side of the powertransformer 908. The outputs of the first and second voltage sensingcircuits 912, 924 are provided to separate isolations transformers 916,922 and the output of the current sensing circuit 914 is provided toanother isolation transformer 916. The digitized voltage and currentsensing measurements from the ADC circuit 926 are provided the processor902 for computing impedance. As an example, the first energy modalityENERGY₁ may be ultrasonic energy and the second energy modality ENERGY₂may be RF energy. Nevertheless, in addition to ultrasonic and bipolar ormonopolar RF energy modalities, other energy modalities includeirreversible and/or reversible electroporation and/or microwave energy,among others. Also, although the example illustrated in FIG. 2 shows asingle return path RETURN may be provided for two or more energymodalities, in other aspects, multiple return paths RETURN_(n) may beprovided for each energy modality ENERGY_(n). Thus, as described herein,the ultrasonic transducer impedance may be measured by dividing theoutput of the first voltage sensing circuit 912 by the current sensingcircuit 914 and the tissue impedance may be measured by dividing theoutput of the second voltage sensing circuit 924 by the current sensingcircuit 914.

As shown in FIG. 2, the generator 900 comprising at least one outputport can include a power transformer 908 with a single output and withmultiple taps to provide power in the form of one or more energymodalities, such as ultrasonic, bipolar or monopolar RF, irreversibleand/or reversible electroporation, and/or microwave energy, amongothers, for example, to the end effector depending on the type oftreatment of tissue being performed. For example, the generator 900 candeliver energy with higher voltage and lower current to drive anultrasonic transducer, with lower voltage and higher current to drive RFelectrodes for sealing tissue, or with a coagulation waveform for spotcoagulation using either monopolar or bipolar RF electrosurgicalelectrodes. The output waveform from the generator 900 can be steered,switched, or filtered to provide the frequency to the end effector ofthe surgical instrument. The connection of an ultrasonic transducer tothe generator 900 output would be preferably located between the outputlabeled ENERGY₁ and RETURN as shown in FIG. 2. In one example, aconnection of RF bipolar electrodes to the generator 900 output would bepreferably located between the output labeled ENERGY₂ and RETURN. In thecase of monopolar output, the preferred connections would be activeelectrode (e.g., pencil or other probe) to the ENERGY₂ output and asuitable return pad connected to the RETURN output.

Additional details are disclosed in U.S. Patent Application PublicationNo. 2017/0086914, titled TECHNIQUES FOR OPERATING GENERATOR FORDIGITALLY GENERATING ELECTRICAL SIGNAL WAVEFORMS AND SURGICALINSTRUMENTS, which published on Mar. 30, 2017, which is hereinincorporated by reference in its entirety.

As used throughout this description, the term “wireless” and itsderivatives may be used to describe circuits, devices, systems, methods,techniques, communications channels, etc., that may communicate datathrough the use of modulated electromagnetic radiation through anon-solid medium. The term does not imply that the associated devices donot contain any wires, although in some aspects they might not. Thecommunication module may implement any of a number of wireless or wiredcommunication standards or protocols, including but not limited to W-Fi(IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE 802.20, long termevolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS, CDMA,TDMA, DECT, Bluetooth, Ethernet derivatives thereof, as well as anyother wireless and wired protocols that are designated as 3G, 4G, 5G,and beyond. The computing module may include a plurality ofcommunication modules. For instance, a first communication module may bededicated to shorter range wireless communications such as Wi-Fi andBluetooth and a second communication module may be dedicated to longerrange wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE,Ev-DO, and others.

As used herein a processor or processing unit is an electronic circuitwhich performs operations on some external data source, usually memoryor some other data stream. The term is used herein to refer to thecentral processor (central processing unit) in a system or computersystems (especially systems on a chip (SoCs)) that combine a number ofspecialized “processors.”

As used herein, a system on a chip or system on chip (SoC or SOC) is anintegrated circuit (also known as an “IC” or “chip”) that integrates allcomponents of a computer or other electronic systems. It may containdigital, analog, mixed-signal, and often radio-frequency functions—allon a single substrate. A SoC integrates a microcontroller (ormicroprocessor) with advanced peripherals like graphics processing unit(GPU), W-Fi module, or coprocessor. A SoC may or may not containbuilt-in memory.

As used herein, a microcontroller or controller is a system thatintegrates a microprocessor with peripheral circuits and memory. Amicrocontroller (or MCU for microcontroller unit) may be implemented asa small computer on a single integrated circuit. It may be similar to aSoC; an SoC may include a microcontroller as one of its components. Amicrocontroller may contain one or more core processing units (CPUs)along with memory and programmable input/output peripherals. Programmemory in the form of Ferroelectric RAM, NOR flash or OTP ROM is alsooften included on chip, as well as a small amount of RAM.Microcontrollers may be employed for embedded applications, in contrastto the microprocessors used in personal computers or other generalpurpose applications consisting of various discrete chips.

As used herein, the term controller or microcontroller may be astand-alone IC or chip device that interfaces with a peripheral device.This may be a link between two parts of a computer or a controller on anexternal device that manages the operation of (and connection with) thatdevice.

Any of the processors or microcontrollers described herein, may beimplemented by any single core or multicore processor such as thoseknown under the trade name ARM Cortex by Texas Instruments. In oneaspect, the processor may be an LM4F230H5QR ARM Cortex-M4F ProcessorCore, available from Texas Instruments, for example, comprising on-chipmemory of 256 KB single-cycle flash memory, or other non-volatilememory, up to 40 MHz, a prefetch buffer to improve performance above 40MHz, a 32 KB single-cycle serial random access memory (SRAM), internalread-only memory (ROM) loaded with StellarisWare® software, 2 KBelectrically erasable programmable read-only memory (EEPROM), one ormore pulse width modulation (PWM) modules, one or more quadratureencoder inputs (QEI) analog, one or more 12-bit Analog-to-DigitalConverters (ADC) with 12 analog input channels, details of which areavailable for the product datasheet.

In one aspect, the processor may comprise a safety controller comprisingtwo controller-based families such as TMS570 and RM4x known under thetrade name Hercules ARM Cortex R4, also by Texas Instruments. The safetycontroller may be configured specifically for IEC 61508 and ISO 26262safety critical applications, among others, to provide advancedintegrated safety features while delivering scalable performance,connectivity, and memory options.

Modular devices include the modules (as described in connection withFIG. 3, for example) that are receivable within a surgical hub and thesurgical devices or instruments that can be connected to the variousmodules in order to connect or pair with the corresponding surgical hub.The modular devices include, for example, intelligent surgicalinstruments, medical imaging devices, suction/irrigation devices, smokeevacuators, energy generators, ventilators, insufflators, and displays.The modular devices described herein can be controlled by controlalgorithms. The control algorithms can be executed on the modular deviceitself, on the surgical hub to which the particular modular device ispaired, or on both the modular device and the surgical hub (e.g., via adistributed computing architecture). In some exemplifications, themodular devices' control algorithms control the devices based on datasensed by the modular device itself (i.e., by sensors in, on, orconnected to the modular device). This data can be related to thepatient being operated on (e.g., tissue properties or insufflationpressure) or the modular device itself (e.g., the rate at which a knifeis being advanced, motor current, or energy levels). For example, acontrol algorithm for a surgical stapling and cutting instrument cancontrol the rate at which the instrument's motor drives its knifethrough tissue according to resistance encountered by the knife as itadvances.

FIG. 3 illustrates one form of a surgical system 1000 comprising agenerator 1100 and various surgical instruments 1104, 1106, 1108 usabletherewith, where the surgical instrument 1104 is an ultrasonic surgicalinstrument, the surgical instrument 1106 is an RF electrosurgicalinstrument, and the multifunction surgical instrument 1108 is acombination ultrasonic/RF electrosurgical instrument. The generator 1100is configurable for use with a variety of surgical instruments.According to various forms, the generator 1100 may be configurable foruse with different surgical instruments of different types including,for example, ultrasonic surgical instruments 1104, RF electrosurgicalinstruments 1106, and multifunction surgical instruments 1108 thatintegrate RF and ultrasonic energies delivered simultaneously from thegenerator 1100. Although in the form of FIG. 3 the generator 1100 isshown separate from the surgical instruments 1104, 1106, 1108 in oneform, the generator 1100 may be formed integrally with any of thesurgical instruments 1104, 1106, 1108 to form a unitary surgical system.The generator 1100 comprises an input device 1110 located on a frontpanel of the generator 1100 console. The input device 1110 may compriseany suitable device that generates signals suitable for programming theoperation of the generator 1100. The generator 1100 may be configuredfor wired or wireless communication.

The generator 1100 is configured to drive multiple surgical instruments1104, 1106, 1108. The first surgical instrument is an ultrasonicsurgical instrument 1104 and comprises a handpiece 1105 (HP), anultrasonic transducer 1120, a shaft 1126, and an end effector 1122. Theend effector 1122 comprises an ultrasonic blade 1128 acousticallycoupled to the ultrasonic transducer 1120 and a clamp arm 1140. Thehandpiece 1105 comprises a trigger 1143 to operate the clamp arm 1140and a combination of the toggle buttons 1134 a, 1134 b, 1134 c toenergize and drive the ultrasonic blade 1128 or other function. Thetoggle buttons 1134 a, 1134 b, 1134 c can be configured to energize theultrasonic transducer 1120 with the generator 1100.

The generator 1100 also is configured to drive a second surgicalinstrument 1106. The second surgical instrument 1106 is an RFelectrosurgical instrument and comprises a handpiece 1107 (HP), a shaft1127, and an end effector 1124. The end effector 1124 compriseselectrodes in clamp arms 1142 a, 1142 b and return through an electricalconductor portion of the shaft 1127. The electrodes are coupled to andenergized by a bipolar energy source within the generator 1100. Thehandpiece 1107 comprises a trigger 1145 to operate the clamp arms 1142a, 1142 b and an energy button 1135 to actuate an energy switch toenergize the electrodes in the end effector 1124.

The generator 1100 also is configured to drive a multifunction surgicalinstrument 1108. The multifunction surgical instrument 1108 comprises ahandpiece 1109 (HP), a shaft 1129, and an end effector 1125. The endeffector 1125 comprises an ultrasonic blade 1149 and a clamp arm 1146.The ultrasonic blade 1149 is acoustically coupled to the ultrasonictransducer 1120. The handpiece 1109 comprises a trigger 1147 to operatethe clamp arm 1146 and a combination of the toggle buttons 1137 a, 1137b, 1137 c to energize and drive the ultrasonic blade 1149 or otherfunction. The toggle buttons 1137 a, 1137 b, 1137 c can be configured toenergize the ultrasonic transducer 1120 with the generator 1100 andenergize the ultrasonic blade 1149 with a bipolar energy source alsocontained within the generator 1100.

The generator 1100 is configurable for use with a variety of surgicalinstruments. According to various forms, the generator 1100 may beconfigurable for use with different surgical instruments of differenttypes including, for example, the ultrasonic surgical instrument 1104,the RF electrosurgical instrument 1106, and the multifunction surgicalinstrument 1108 that integrates RF and ultrasonic energies deliveredsimultaneously from the generator 1100. Although in the form of FIG. 3the generator 1100 is shown separate from the surgical instruments 1104,1106, 1108, in another form the generator 1100 may be formed integrallywith any one of the surgical instruments 1104, 1106, 1108 to form aunitary surgical system. As discussed above, the generator 1100comprises an input device 1110 located on a front panel of the generator1100 console. The input device 1110 may comprise any suitable devicethat generates signals suitable for programming the operation of thegenerator 1100. The generator 1100 also may comprise one or more outputdevices 1112. Further aspects of generators for digitally generatingelectrical signal waveforms and surgical instruments are described in USpatent publication US-2017-0086914-A1, which is herein incorporated byreference in its entirety.

FIG. 4 is an end effector 1122 of the example ultrasonic device 1104, inaccordance with at least one aspect of the present disclosure. The endeffector 1122 may comprise a blade 1128 that may be coupled to theultrasonic transducer 1120 via a wave guide. When driven by theultrasonic transducer 1120, the blade 1128 may vibrate and, when broughtinto contact with tissue, may cut and/or coagulate the tissue, asdescribed herein. According to various aspects, and as illustrated inFIG. 4, the end effector 1122 may also comprise a clamp arm 1140 thatmay be configured for cooperative action with the blade 1128 of the endeffector 1122. With the blade 1128, the clamp arm 1140 may comprise aset of jaws. The clamp arm 1140 may be pivotally connected at a distalend of a shaft 1126 of the instrument portion 1104. The clamp arm 1140may include a clamp arm tissue pad 1163, which may be formed fromTEFLON® or other suitable low-friction material. The pad 1163 may bemounted for cooperation with the blade 1128, with pivotal movement ofthe clamp arm 1140 positioning the clamp pad 1163 in substantiallyparallel relationship to, and in contact with, the blade 1128. By thisconstruction, a tissue bite to be clamped may be grasped between thetissue pad 1163 and the blade 1128. The tissue pad 1163 may be providedwith a sawtooth-like configuration including a plurality of axiallyspaced, proximally extending gripping teeth 1161 to enhance the grippingof tissue in cooperation with the blade 1128. The clamp arm 1140 maytransition from the open position shown in FIG. 4 to a closed position(with the clamp arm 1140 in contact with or proximity to the blade 1128)in any suitable manner. For example, the handpiece 1105 may comprise ajaw closure trigger. When actuated by a clinician, the jaw closuretrigger may pivot the clamp arm 1140 in any suitable manner.

The generator 1100 may be activated to provide the drive signal to theultrasonic transducer 1120 in any suitable manner. For example, thegenerator 1100 may comprise a foot switch 1430 (FIG. 5) coupled to thegenerator 1100 via a footswitch cable 1432. A clinician may activate theultrasonic transducer 1120, and thereby the ultrasonic transducer 1120and blade 1128, by depressing the foot switch 1430. In addition, orinstead of the foot switch 1430, some aspects of the device 1104 mayutilize one or more switches positioned on the handpiece 1105 that, whenactivated, may cause the generator 1100 to activate the ultrasonictransducer 1120. In one aspect, for example, the one or more switchesmay comprise a pair of toggle buttons 1134, 1134 a, 1134 b (FIG. 3), forexample, to determine an operating mode of the device 1104. When thetoggle button 1134 a is depressed, for example, the ultrasonic generator1100 may provide a maximum drive signal to the ultrasonic transducer1120, causing it to produce maximum ultrasonic energy output. Depressingtoggle button 1134 b may cause the ultrasonic generator 1100 to providea user-selectable drive signal to the ultrasonic transducer 1120,causing it to produce less than the maximum ultrasonic energy output.The device 1104 additionally or alternatively may comprise a secondswitch to, for example, indicate a position of a jaw closure trigger foroperating the jaws via the clamp arm 1140 of the end effector 1122.Also, in some aspects, the ultrasonic generator 1100 may be activatedbased on the position of the jaw closure trigger, (e.g., as theclinician depresses the jaw closure trigger to close the jaws via theclamp arm 1140, ultrasonic energy may be applied).

Additionally or alternatively, the one or more switches may comprise atoggle button 1134 that, when depressed, causes the generator 1100 toprovide a pulsed output (FIG. 3). The pulses may be provided at anysuitable frequency and grouping, for example. In certain aspects, thepower level of the pulses may be the power levels associated with togglebuttons 1134 a, 1134 b (maximum, less than maximum), for example.

It will be appreciated that a device 1104 may comprise any combinationof the toggle buttons 1134 a, 1134 b, 1134 (FIG. 3). For example, thedevice 1104 could be configured to have only two toggle buttons: atoggle button 1134 a for producing maximum ultrasonic energy output anda toggle button 1134 for producing a pulsed output at either the maximumor less than maximum power level per. In this way, the drive signaloutput configuration of the generator 1100 could be five continuoussignals, or any discrete number of individual pulsed signals (1, 2, 3,4, or 5). In certain aspects, the specific drive signal configurationmay be controlled based upon, for example, EEPROM settings in thegenerator 1100 and/or user power level selection(s).

In certain aspects, a two-position switch may be provided as analternative to a toggle button 1134 (FIG. 3). For example, a device 1104may include a toggle button 1134 a for producing a continuous output ata maximum power level and a two-position toggle button 1134 b. In afirst detented position, toggle button 1134 b may produce a continuousoutput at a less than maximum power level, and in a second detentedposition the toggle button 1134 b may produce a pulsed output (e.g., ateither a maximum or less than maximum power level, depending upon theEEPROM settings).

In some aspects, the RF electrosurgical end effector 1124, 1125 (FIG. 3)may also comprise a pair of electrodes. The electrodes may be incommunication with the generator 1100, for example, via a cable. Theelectrodes may be used, for example, to measure an impedance of a tissuebite present between the clamp arm 1142 a, 1146 and the blade 1142 b,1149. The generator 1100 may provide a signal (e.g., a non-therapeuticsignal) to the electrodes. The impedance of the tissue bite may befound, for example, by monitoring the current, voltage, etc. of thesignal.

In various aspects, the generator 1100 may comprise several separatefunctional elements, such as modules and/or blocks, as shown in FIG. 5,a diagram of the surgical system 1000 of FIG. 3. Different functionalelements or modules may be configured for driving the different kinds ofsurgical devices 1104, 1106, 1108. For example an ultrasonic generatormodule may drive an ultrasonic device, such as the ultrasonic device1104. An electrosurgery/RF generator module may drive theelectrosurgical device 1106. The modules may generate respective drivesignals for driving the surgical devices 1104, 1106, 1108. In variousaspects, the ultrasonic generator module and/or the electrosurgery/RFgenerator module each may be formed integrally with the generator 1100.Alternatively, one or more of the modules may be provided as a separatecircuit module electrically coupled to the generator 1100. (The modulesare shown in phantom to illustrate this option.) Also, in some aspects,the electrosurgery/RF generator module may be formed integrally with theultrasonic generator module, or vice versa.

In accordance with the described aspects, the ultrasonic generatormodule may produce a drive signal or signals of particular voltages,currents, and frequencies (e.g. 55,500 cycles per second, or Hz). Thedrive signal or signals may be provided to the ultrasonic device 1104,and specifically to the transducer 1120, which may operate, for example,as described above. In one aspect, the generator 1100 may be configuredto produce a drive signal of a particular voltage, current, and/orfrequency output signal that can be stepped with high resolution,accuracy, and repeatability.

In accordance with the described aspects, the electrosurgery/RFgenerator module may generate a drive signal or signals with outputpower sufficient to perform bipolar electrosurgery using radio frequency(RF) energy. In bipolar electrosurgery applications, the drive signalmay be provided, for example, to the electrodes of the electrosurgicaldevice 1106, for example, as described above. Accordingly, the generator1100 may be configured for therapeutic purposes by applying electricalenergy to the tissue sufficient for treating the tissue (e.g.,coagulation, cauterization, tissue welding, etc.).

The generator 1100 may comprise an input device 2150 (FIG. 8B) located,for example, on a front panel of the generator 1100 console. The inputdevice 2150 may comprise any suitable device that generates signalssuitable for programming the operation of the generator 1100. Inoperation, the user can program or otherwise control operation of thegenerator 1100 using the input device 2150. The input device 2150 maycomprise any suitable device that generates signals that can be used bythe generator (e.g., by one or more processors contained in thegenerator) to control the operation of the generator 1100 (e.g.,operation of the ultrasonic generator module and/or electrosurgery/RFgenerator module). In various aspects, the input device 2150 includesone or more of: buttons, switches, thumbwheels, keyboard, keypad, touchscreen monitor, pointing device, remote connection to a general purposeor dedicated computer. In other aspects, the input device 2150 maycomprise a suitable user interface, such as one or more user interfacescreens displayed on a touch screen monitor, for example. Accordingly,by way of the input device 2150, the user can set or program variousoperating parameters of the generator, such as, for example, current(I), voltage (V), frequency (f), and/or period (T) of a drive signal orsignals generated by the ultrasonic generator module and/orelectrosurgery/RF generator module.

The generator 1100 may also comprise an output device 2140 (FIG. 8B)located, for example, on a front panel of the generator 1100 console.The output device 2140 includes one or more devices for providing asensory feedback to a user. Such devices may comprise, for example,visual feedback devices (e.g., an LCD display screen, LED indicators),audio feedback devices (e.g., a speaker, a buzzer) or tactile feedbackdevices (e.g., haptic actuators).

Although certain modules and/or blocks of the generator 1100 may bedescribed by way of example, it can be appreciated that a greater orlesser number of modules and/or blocks may be used and still fall withinthe scope of the aspects. Further, although various aspects may bedescribed in terms of modules and/or blocks to facilitate description,such modules and/or blocks may be implemented by one or more hardwarecomponents, e.g., processors, Digital Signal Processors (DSPs),Programmable Logic Devices (PLDs), Application Specific IntegratedCircuits (ASICs), circuits, registers and/or software components, e.g.,programs, subroutines, logic and/or combinations of hardware andsoftware components.

In one aspect, the ultrasonic generator drive module andelectrosurgery/RF drive module 1110 (FIG. 3) may comprise one or moreembedded applications implemented as firmware, software, hardware, orany combination thereof. The modules may comprise various executablemodules such as software, programs, data, drivers, application programinterfaces (APIs), and so forth. The firmware may be stored innonvolatile memory (NVM), such as in bit-masked read-only memory (ROM)or flash memory. In various implementations, storing the firmware in ROMmay preserve flash memory. The NVM may comprise other types of memoryincluding, for example, programmable ROM (PROM), erasable programmableROM (EPROM), electrically erasable programmable ROM (EEPROM), or batterybacked random-access memory (RAM) such as dynamic RAM (DRAM),Double-Data-Rate DRAM (DDRAM), and/or synchronous DRAM (SDRAM).

In one aspect, the modules comprise a hardware component implemented asa processor for executing program instructions for monitoring variousmeasurable characteristics of the devices 1104, 1106, 1108 andgenerating a corresponding output drive signal or signals for operatingthe devices 1104, 1106, 1108. In aspects in which the generator 1100 isused in conjunction with the device 1104, the drive signal may drive theultrasonic transducer 1120 in cutting and/or coagulation operatingmodes. Electrical characteristics of the device 1104 and/or tissue maybe measured and used to control operational aspects of the generator1100 and/or provided as feedback to the user. In aspects in which thegenerator 1100 is used in conjunction with the device 1106, the drivesignal may supply electrical energy (e.g., RF energy) to the endeffector 1124 in cutting, coagulation and/or desiccation modes.Electrical characteristics of the device 1106 and/or tissue may bemeasured and used to control operational aspects of the generator 1100and/or provided as feedback to the user. In various aspects, aspreviously discussed, the hardware components may be implemented as DSP,PLD, ASIC, circuits, and/or registers. In one aspect, the processor maybe configured to store and execute computer software programinstructions to generate the step function output signals for drivingvarious components of the devices 1104, 1106, 1108, such as theultrasonic transducer 1120 and the end effectors 1122, 1124, 1125.

An electromechanical ultrasonic system includes an ultrasonictransducer, a waveguide, and an ultrasonic blade. The electromechanicalultrasonic system has an initial resonant frequency defined by thephysical properties of the ultrasonic transducer, the waveguide, and theultrasonic blade. The ultrasonic transducer is excited by an alternatingvoltage V_(g)(t) and current I_(g)(t) signal equal to the resonantfrequency of the electromechanical ultrasonic system. When theelectromechanical ultrasonic system is at resonance, the phasedifference between the voltage V_(g)(t) and current I_(g)(t) signals iszero. Stated another way, at resonance the inductive impedance is equalto the capacitive impedance. As the ultrasonic blade heats up, thecompliance of the ultrasonic blade (modeled as an equivalentcapacitance) causes the resonant frequency of the electromechanicalultrasonic system to shift. Thus, the inductive impedance is no longerequal to the capacitive impedance causing a mismatch between the drivefrequency and the resonant frequency of the electromechanical ultrasonicsystem. The system is now operating “off-resonance.” The mismatchbetween the drive frequency and the resonant frequency is manifested asa phase difference between the voltage V_(g)(t) and current I_(g)(t)signals applied to the ultrasonic transducer. The generator electronicscan easily monitor the phase difference between the voltage V_(g)(t) andcurrent I_(g)(t) signals and can continuously adjust the drive frequencyuntil the phase difference is once again zero. At this point, the newdrive frequency is equal to the new resonant frequency of theelectromechanical ultrasonic system. The change in phase and/orfrequency can be used as an indirect measurement of the ultrasonic bladetemperature.

As shown in FIG. 6, the electromechanical properties of the ultrasonictransducer may be modeled as an equivalent circuit comprising a firstbranch having a static capacitance and a second “motional” branch havinga serially connected inductance, resistance and capacitance that definethe electromechanical properties of a resonator. Known ultrasonicgenerators may include a tuning inductor for tuning out the staticcapacitance at a resonant frequency so that substantially all ofgenerator's drive signal current flows into the motional branch.Accordingly, by using a tuning inductor, the generator's drive signalcurrent represents the motional branch current, and the generator isthus able to control its drive signal to maintain the ultrasonictransducer's resonant frequency. The tuning inductor may also transformthe phase impedance plot of the ultrasonic transducer to improve thegenerator's frequency lock capabilities. However, the tuning inductormust be matched with the specific static capacitance of an ultrasonictransducer at the operational resonance frequency. In other words, adifferent ultrasonic transducer having a different static capacitancerequires a different tuning inductor.

FIG. 6 illustrates an equivalent circuit 1500 of an ultrasonictransducer, such as the ultrasonic transducer 1120, according to oneaspect. The circuit 1500 comprises a first “motional” branch having aserially connected inductance L_(s), resistance R_(s) and capacitanceC_(s) that define the electromechanical properties of the resonator, anda second capacitive branch having a static capacitance C₀. Drive currentI_(g)(t) may be received from a generator at a drive voltage V_(g)(t),with motional current I_(m)(t) flowing through the first branch andcurrent I_(g)(t)-I_(m)(t) flowing through the capacitive branch. Controlof the electromechanical properties of the ultrasonic transducer may beachieved by suitably controlling I_(g)(t) and V_(g)(t). As explainedabove, known generator architectures may include a tuning inductor L_(t)(shown in phantom in FIG. 6) in a parallel resonance circuit for tuningout the static capacitance C₀ at a resonant frequency so thatsubstantially all of the generator's current output I_(g)(t) flowsthrough the motional branch. In this way, control of the motional branchcurrent I_(m)(t) is achieved by controlling the generator current outputI_(g)(t). The tuning inductor L_(t) is specific to the staticcapacitance C₀ of an ultrasonic transducer, however, and a differentultrasonic transducer having a different static capacitance requires adifferent tuning inductor L_(t). Moreover, because the tuning inductorL_(t) is matched to the nominal value of the static capacitance C₀ at asingle resonant frequency, accurate control of the motional branchcurrent I_(m)(t) is assured only at that frequency. As frequency shiftsdown with transducer temperature, accurate control of the motionalbranch current is compromised.

Various aspects of the generator 1100 may not rely on a tuning inductorL_(t) to monitor the motional branch current I_(m)(t). Instead, thegenerator 1100 may use the measured value of the static capacitance C₀in between applications of power for a specific ultrasonic surgicaldevice 1104 (along with drive signal voltage and current feedback data)to determine values of the motional branch current I_(m)(t) on a dynamicand ongoing basis (e.g., in real-time). Such aspects of the generator1100 are therefore able to provide virtual tuning to simulate a systemthat is tuned or resonant with any value of static capacitance C₀ at anyfrequency, and not just at a single resonant frequency dictated by anominal value of the static capacitance C₀.

FIG. 7 is a simplified block diagram of one aspect of the generator 1100for providing inductorless tuning as described above, among otherbenefits. FIGS. 8A-8C illustrate an architecture of the generator 1100of FIG. 7 according to one aspect. With reference to FIG. 7, thegenerator 1100 may comprise a patient isolated stage 1520 incommunication with a non-isolated stage 1540 via a power transformer1560. A secondary winding 1580 of the power transformer 1560 iscontained in the isolated stage 1520 and may comprise a tappedconfiguration (e.g., a center-tapped or non-center tapped configuration)to define drive signal outputs 1600 a, 1600 b, 1600 c for outputtingdrive signals to different surgical devices, such as, for example, anultrasonic surgical device 1104 and an electrosurgical device 1106. Inparticular, drive signal outputs 1600 a, 1600 b, 1600 c may output adrive signal (e.g., a 420V RMS drive signal) to an ultrasonic surgicaldevice 1104, and drive signal outputs 1600 a, 1600 b, 1600 c may outputa drive signal (e.g., a 100V RMS drive signal) to an electrosurgicaldevice 1106, with output 1600 b corresponding to the center tap of thepower transformer 1560. The non-isolated stage 1540 may comprise a poweramplifier 1620 having an output connected to a primary winding 1640 ofthe power transformer 1560. In certain aspects the power amplifier 1620may comprise a push-pull amplifier, for example. The non-isolated stage1540 may further comprise a programmable logic device 1660 for supplyinga digital output to a digital-to-analog converter (DAC) 1680, which inturn supplies a corresponding analog signal to an input of the poweramplifier 1620. In certain aspects the programmable logic device 1660may comprise a field-programmable gate array (FPGA), for example. Theprogrammable logic device 1660, by virtue of controlling the poweramplifier's 1620 input via the DAC 1680, may therefore control any of anumber of parameters (e.g., frequency, waveform shape, waveformamplitude) of drive signals appearing at the drive signal outputs 1600a, 1600 b, 1600 c. In certain aspects and as discussed below, theprogrammable logic device 1660, in conjunction with a processor (e.g.,processor 1740 discussed below), may implement a number of digitalsignal processing (DSP)-based and/or other control algorithms to controlparameters of the drive signals output by the generator 1100.

Power may be supplied to a power rail of the power amplifier 1620 by aswitch-mode regulator 1700. In certain aspects the switch-mode regulator1700 may comprise an adjustable buck regulator, for example. Asdiscussed above, the non-isolated stage 1540 may further comprise aprocessor 1740, which in one aspect may comprise a DSP processor such asan ADSP-21469 SHARC DSP, available from Analog Devices, Norwood, Mass.,for example. In certain aspects the processor 1740 may control operationof the switch-mode power converter 1700 responsive to voltage feedbackdata received from the power amplifier 1620 by the processor 1740 via ananalog-to-digital converter (ADC) 1760. In one aspect, for example, theprocessor 1740 may receive as input, via the ADC 1760, the waveformenvelope of a signal (e.g., an RF signal) being amplified by the poweramplifier 1620. The processor 1740 may then control the switch-moderegulator 1700 (e.g., via a pulse-width modulated (PWM) output) suchthat the rail voltage supplied to the power amplifier 1620 tracks thewaveform envelope of the amplified signal. By dynamically modulating therail voltage of the power amplifier 1620 based on the waveform envelope,the efficiency of the power amplifier 1620 may be significantly improvedrelative to a fixed rail voltage amplifier scheme. The processor 1740may be configured for wired or wireless communication.

In certain aspects and as discussed in further detail in connection withFIGS. 9A-9B, the programmable logic device 1660, in conjunction with theprocessor 1740, may implement a direct digital synthesizer (DDS) controlscheme to control the waveform shape, frequency and/or amplitude ofdrive signals output by the generator 1100. In one aspect, for example,the programmable logic device 1660 may implement a DDS control algorithm2680 (FIG. 9A) by recalling waveform samples stored in adynamically-updated look-up table (LUT), such as a RAM LUT which may beembedded in an FPGA. This control algorithm is particularly useful forultrasonic applications in which an ultrasonic transducer, such as theultrasonic transducer 1120, may be driven by a clean sinusoidal currentat its resonant frequency. Because other frequencies may exciteparasitic resonances, minimizing or reducing the total distortion of themotional branch current may correspondingly minimize or reduceundesirable resonance effects. Because the waveform shape of a drivesignal output by the generator 1100 is impacted by various sources ofdistortion present in the output drive circuit (e.g., the powertransformer 1560, the power amplifier 1620), voltage and currentfeedback data based on the drive signal may be input into an algorithm,such as an error control algorithm implemented by the processor 1740,which compensates for distortion by suitably pre-distorting or modifyingthe waveform samples stored in the LUT on a dynamic, ongoing basis(e.g., in real-time). In one aspect, the amount or degree ofpre-distortion applied to the LUT samples may be based on the errorbetween a computed motional branch current and a desired currentwaveform shape, with the error being determined on a sample-by samplebasis. In this way, the pre-distorted LUT samples, when processedthrough the drive circuit, may result in a motional branch drive signalhaving the desired waveform shape (e.g., sinusoidal) for optimallydriving the ultrasonic transducer. In such aspects, the LUT waveformsamples will therefore not represent the desired waveform shape of thedrive signal, but rather the waveform shape that is required toultimately produce the desired waveform shape of the motional branchdrive signal when distortion effects are taken into account.

The non-isolated stage 1540 may further comprise an ADC 1780 and an ADC1800 coupled to the output of the power transformer 1560 via respectiveisolation transformers 1820, 1840 for respectively sampling the voltageand current of drive signals output by the generator 1100. In certainaspects, the ADCs 1780, 1800 may be configured to sample at high speeds(e.g., 80 Msps) to enable oversampling of the drive signals. In oneaspect, for example, the sampling speed of the ADCs 1780, 1800 mayenable approximately 200× (depending on drive frequency) oversampling ofthe drive signals. In certain aspects, the sampling operations of theADCs 1780, 1800 may be performed by a single ADC receiving input voltageand current signals via a two-way multiplexer. The use of high-speedsampling in aspects of the generator 1100 may enable, among otherthings, calculation of the complex current flowing through the motionalbranch (which may be used in certain aspects to implement DDS-basedwaveform shape control described above), accurate digital filtering ofthe sampled signals, and calculation of real power consumption with ahigh degree of precision. Voltage and current feedback data output bythe ADCs 1780, 1800 may be received and processed (e.g., FIFO buffering,multiplexing) by the programmable logic device 1660 and stored in datamemory for subsequent retrieval by, for example, the processor 1740. Asnoted above, voltage and current feedback data may be used as input toan algorithm for pre-distorting or modifying LUT waveform samples on adynamic and ongoing basis. In certain aspects, this may require eachstored voltage and current feedback data pair to be indexed based on, orotherwise associated with, a corresponding LUT sample that was output bythe programmable logic device 1660 when the voltage and current feedbackdata pair was acquired. Synchronization of the LUT samples and thevoltage and current feedback data in this manner contributes to thecorrect timing and stability of the pre-distortion algorithm.

In certain aspects, the voltage and current feedback data may be used tocontrol the frequency and/or amplitude (e.g., current amplitude) of thedrive signals. In one aspect, for example, voltage and current feedbackdata may be used to determine impedance phase, e.g., the phasedifference between the voltage and current drive signals. The frequencyof the drive signal may then be controlled to minimize or reduce thedifference between the determined impedance phase and an impedance phasesetpoint (e.g., 0°), thereby minimizing or reducing the effects ofharmonic distortion and correspondingly enhancing impedance phasemeasurement accuracy. The determination of phase impedance and afrequency control signal may be implemented in the processor 1740, forexample, with the frequency control signal being supplied as input to aDDS control algorithm implemented by the programmable logic device 1660.

The impedance phase may be determined through Fourier analysis. In oneaspect, the phase difference between the generator voltage V_(g)(t) andgenerator current I_(g)(t) driving signals may be determined using theFast Fourier Transform (FFT) or the Discrete Fourier Transform (DFT) asfollows:

V_(g)(t) = A₁cos  (2π f₀t + ϕ₁)I_(g)(t) = A₂ cos  (2π f₀t + ϕ₂)${V_{g}(f)} = {\frac{A_{1}}{2}\left( {{\delta \left( {f - f_{0}} \right)} + {\delta \left( {f + f_{0}} \right)}} \right)\exp \; \left( {j\; 2\pi \; f\frac{\phi_{1}}{2\pi \; f_{0}}} \right)}$${I_{g}(f)} = {\frac{A_{2}}{2}\left( {{\delta \left( {f - f_{0}} \right)} + {\delta \left( {f + f_{0}} \right)}} \right)\; \exp \; \left( {j\; 2\pi \; f\frac{\phi_{2}}{2\pi \; f_{0}}} \right)}$

Evaluating the Fourier Transform at the frequency of the sinusoidyields:

$\begin{matrix}{{V_{g}\left( f_{0} \right)} = {\frac{A_{1}}{2}\; {\delta (0)}\mspace{11mu} \exp \; \left( {j\; \phi_{1}} \right)}} & {{\arg {\; \;}V\; \left( f_{0} \right)} = \phi_{1}} \\{{I_{g}\left( f_{0} \right)} = {\frac{A_{2}}{2}{\delta (0)}\; \exp \; \left( {j\; \phi_{2}} \right)}} & {{\arg \mspace{11mu} {I\left( f_{0} \right)}} = \phi_{2}}\end{matrix}$

Other approaches include weighted least-squares estimation, Kalmanfiltering, and space-vector-based techniques. Virtually all of theprocessing in an FFT or DFT technique may be performed in the digitaldomain with the aid of the 2-channel high speed ADC 1780, 1800, forexample. In one technique, the digital signal samples of the voltage andcurrent signals are Fourier transformed with an FFT or a DFT. The phaseangle φ at any point in time can be calculated by:

φ=2πf t+φ ₀

where φ is the phase angle, f is the frequency, t is time, and φ₀ is thephase at t=0.

Another technique for determining the phase difference between thevoltage V_(g)(t) and current I_(g)(t) signals is the zero-crossingmethod and produces highly accurate results. For voltage V_(g)(t) andcurrent I_(g)(t) signals having the same frequency, each negative topositive zero-crossing of voltage signal V_(g)(t) triggers the start ofa pulse, while each negative to positive zero-crossing of current signalI_(g)(t) triggers the end of the pulse. The result is a pulse train witha pulse width proportional to the phase angle between the voltage signaland the current signal. In one aspect, the pulse train may be passedthrough an averaging filter to yield a measure of the phase difference.Furthermore, if the positive to negative zero crossings also are used ina similar manner, and the results averaged, any effects of DC andharmonic components can be reduced. In one implementation, the analogvoltage V_(g)(t) and current I_(g)(t) signals are converted to digitalsignals that are high if the analog signal is positive and low if theanalog signal is negative. High accuracy phase estimates require sharptransitions between high and low. In one aspect, a Schmitt trigger alongwith an RC stabilization network may be employed to convert the analogsignals into digital signals. In other aspects, an edge triggered RSflip-flop and ancillary circuitry may be employed. In yet anotheraspect, the zero-crossing technique may employ an eXclusive OR (XOR)gate.

Other techniques for determining the phase difference between thevoltage and current signals include Lissajous figures and monitoring theimage; methods such as the three-voltmeter method, the crossed-coilmethod, vector voltmeter and vector impedance methods; and using phasestandard instruments, phase-locked loops, and other techniques asdescribed in Phase Measurement, Peter O'Shea, 2000 CRC Press LLC,<http://www.engnetbase.com>, which is incorporated herein by reference.

In another aspect, for example, the current feedback data may bemonitored in order to maintain the current amplitude of the drive signalat a current amplitude setpoint. The current amplitude setpoint may bespecified directly or determined indirectly based on specified voltageamplitude and power setpoints. In certain aspects, control of thecurrent amplitude may be implemented by control algorithm, such as, forexample, a proportional-integral-derivative (PID) control algorithm, inthe processor 1740. Variables controlled by the control algorithm tosuitably control the current amplitude of the drive signal may include,for example, the scaling of the LUT waveform samples stored in theprogrammable logic device 1660 and/or the full-scale output voltage ofthe DAC 1680 (which supplies the input to the power amplifier 1620) viaa DAC 1860.

The non-isolated stage 1540 may further comprise a processor 1900 forproviding, among other things, user interface (UI) functionality. In oneaspect, the processor 1900 may comprise an Atmel AT91 SAM9263 processorhaving an ARM 926EJ-S core, available from Atmel Corporation, San Jose,Calif., for example. Examples of UI functionality supported by theprocessor 1900 may include audible and visual user feedback,communication with peripheral devices (e.g., via a Universal Serial Bus(USB) interface), communication with a foot switch 1430, communicationwith an input device 2150 (e.g., a touch screen display) andcommunication with an output device 2140 (e.g., a speaker). Theprocessor 1900 may communicate with the processor 1740 and theprogrammable logic device (e.g., via a serial peripheral interface (SPI)bus). Although the processor 1900 may primarily support UIfunctionality, it may also coordinate with the processor 1740 toimplement hazard mitigation in certain aspects. For example, theprocessor 1900 may be programmed to monitor various aspects of userinput and/or other inputs (e.g., touch screen inputs 2150, foot switch1430 inputs, temperature sensor inputs 2160) and may disable the driveoutput of the generator 1100 when an erroneous condition is detected.

In certain aspects, both the processor 1740 (FIGS. 7, 8A) and theprocessor 1900 (FIGS. 7, 8B) may determine and monitor the operatingstate of the generator 1100. For processor 1740, the operating state ofthe generator 1100 may dictate, for example, which control and/ordiagnostic processes are implemented by the processor 1740. Forprocessor 1900, the operating state of the generator 1100 may dictate,for example, which elements of a user interface (e.g., display screens,sounds) are presented to a user. The processors 1740, 1900 mayindependently maintain the current operating state of the generator 1100and recognize and evaluate possible transitions out of the currentoperating state. The processor 1740 may function as the master in thisrelationship and determine when transitions between operating states areto occur. The processor 1900 may be aware of valid transitions betweenoperating states and may confirm if a particular transition isappropriate. For example, when the processor 1740 instructs theprocessor 1900 to transition to a specific state, the processor 1900 mayverify that the requested transition is valid. In the event that arequested transition between states is determined to be invalid by theprocessor 1900, the processor 1900 may cause the generator 1100 to entera failure mode.

The non-isolated stage 1540 may further comprise a controller 1960(FIGS. 7, 8B) for monitoring input devices 2150 (e.g., a capacitivetouch sensor used for turning the generator 1100 on and off, acapacitive touch screen). In certain aspects, the controller 1960 maycomprise at least one processor and/or other controller device incommunication with the processor 1900. In one aspect, for example, thecontroller 1960 may comprise a processor (e.g., a Mega168 8-bitcontroller available from Atmel) configured to monitor user inputprovided via one or more capacitive touch sensors. In one aspect, thecontroller 1960 may comprise a touch screen controller (e.g., a QT5480touch screen controller available from Atmel) to control and manage theacquisition of touch data from a capacitive touch screen.

In certain aspects, when the generator 1100 is in a “power off” state,the controller 1960 may continue to receive operating power (e.g., via aline from a power supply of the generator 1100, such as the power supply2110 (FIG. 7) discussed below). In this way, the controller 1960 maycontinue to monitor an input device 2150 (e.g., a capacitive touchsensor located on a front panel of the generator 1100) for turning thegenerator 1100 on and off. When the generator 1100 is in the “power off”state, the controller 1960 may wake the power supply (e.g., enableoperation of one or more DC/DC voltage converters 2130 (FIG. 7) of thepower supply 2110) if activation of the “on/off” input device 2150 by auser is detected. The controller 1960 may therefore initiate a sequencefor transitioning the generator 1100 to a “power on” state. Conversely,the controller 1960 may initiate a sequence for transitioning thegenerator 1100 to the “power off” state if activation of the “on/off”input device 2150 is detected when the generator 1100 is in the “poweron” state. In certain aspects, for example, the controller 1960 mayreport activation of the “on/off” input device 2150 to the processor1900, which in turn implements the necessary process sequence fortransitioning the generator 1100 to the “power off” state. In suchaspects, the controller 1960 may have no independent ability for causingthe removal of power from the generator 1100 after its “power on” statehas been established.

In certain aspects, the controller 1960 may cause the generator 1100 toprovide audible or other sensory feedback for alerting the user that a“power on” or “power off” sequence has been initiated. Such an alert maybe provided at the beginning of a “power on” or “power off” sequence andprior to the commencement of other processes associated with thesequence.

In certain aspects, the isolated stage 1520 may comprise an instrumentinterface circuit 1980 to, for example, provide a communicationinterface between a control circuit of a surgical device (e.g., acontrol circuit comprising handpiece switches) and components of thenon-isolated stage 1540, such as, for example, the programmable logicdevice 1660, the processor 1740 and/or the processor 1900. Theinstrument interface circuit 1980 may exchange information withcomponents of the non-isolated stage 1540 via a communication link thatmaintains a suitable degree of electrical isolation between the stages1520, 1540, such as, for example, an infrared (IR)-based communicationlink. Power may be supplied to the instrument interface circuit 1980using, for example, a low-dropout voltage regulator powered by anisolation transformer driven from the non-isolated stage 1540.

In one aspect, the instrument interface circuit 1980 may comprise aprogrammable logic device 2000 (e.g., an FPGA) in communication with asignal conditioning circuit 2020 (FIG. 7 and FIG. 8C). The signalconditioning circuit 2020 may be configured to receive a periodic signalfrom the programmable logic device 2000 (e.g., a 2 kHz square wave) togenerate a bipolar interrogation signal having an identical frequency.The interrogation signal may be generated, for example, using a bipolarcurrent source fed by a differential amplifier. The interrogation signalmay be communicated to a surgical device control circuit (e.g., by usinga conductive pair in a cable that connects the generator 1100 to thesurgical device) and monitored to determine a state or configuration ofthe control circuit. For example, the control circuit may comprise anumber of switches, resistors and/or diodes to modify one or morecharacteristics (e.g., amplitude, rectification) of the interrogationsignal such that a state or configuration of the control circuit isuniquely discernible based on the one or more characteristics. In oneaspect, for example, the signal conditioning circuit 2020 may comprisean ADC for generating samples of a voltage signal appearing acrossinputs of the control circuit resulting from passage of interrogationsignal therethrough. The programmable logic device 2000 (or a componentof the non-isolated stage 1540) may then determine the state orconfiguration of the control circuit based on the ADC samples.

In one aspect, the instrument interface circuit 1980 may comprise afirst data circuit interface 2040 to enable information exchange betweenthe programmable logic device 2000 (or other element of the instrumentinterface circuit 1980) and a first data circuit disposed in orotherwise associated with a surgical device. In certain aspects, forexample, a first data circuit 2060 may be disposed in a cable integrallyattached to a surgical device handpiece, or in an adaptor forinterfacing a specific surgical device type or model with the generator1100. In certain aspects, the first data circuit may comprise anon-volatile storage device, such as an electrically erasableprogrammable read-only memory (EEPROM) device. In certain aspects andreferring again to FIG. 7, the first data circuit interface 2040 may beimplemented separately from the programmable logic device 2000 andcomprise suitable circuitry (e.g., discrete logic devices, a processor)to enable communication between the programmable logic device 2000 andthe first data circuit. In other aspects, the first data circuitinterface 2040 may be integral with the programmable logic device 2000.

In certain aspects, the first data circuit 2060 may store informationpertaining to the particular surgical device with which it isassociated. Such information may include, for example, a model number, aserial number, a number of operations in which the surgical device hasbeen used, and/or any other type of information. This information may beread by the instrument interface circuit 1980 (e.g., by the programmablelogic device 2000), transferred to a component of the non-isolated stage1540 (e.g., to programmable logic device 1660, processor 1740 and/orprocessor 1900) for presentation to a user via an output device 2140and/or for controlling a function or operation of the generator 1100.Additionally, any type of information may be communicated to first datacircuit 2060 for storage therein via the first data circuit interface2040 (e.g., using the programmable logic device 2000). Such informationmay comprise, for example, an updated number of operations in which thesurgical device has been used and/or dates and/or times of its usage.

As discussed previously, a surgical instrument may be detachable from ahandpiece (e.g., instrument 1106 may be detachable from handpiece 1107)to promote instrument interchangeability and/or disposability. In suchcases, known generators may be limited in their ability to recognizeparticular instrument configurations being used and to optimize controland diagnostic processes accordingly. The addition of readable datacircuits to surgical device instruments to address this issue isproblematic from a compatibility standpoint, however. For example, itmay be impractical to design a surgical device to maintain backwardcompatibility with generators that lack the requisite data readingfunctionality due to, for example, differing signal schemes, designcomplexity and cost. Other aspects of instruments address these concernsby using data circuits that may be implemented in existing surgicalinstruments economically and with minimal design changes to preservecompatibility of the surgical devices with current generator platforms.

Additionally, aspects of the generator 1100 may enable communicationwith instrument-based data circuits. For example, the generator 1100 maybe configured to communicate with a second data circuit (e.g., a datacircuit) contained in an instrument (e.g., instrument 1104, 1106 or1108) of a surgical device. The instrument interface circuit 1980 maycomprise a second data circuit interface 2100 to enable thiscommunication. In one aspect, the second data circuit interface 2100 maycomprise a tri-state digital interface, although other interfaces mayalso be used. In certain aspects, the second data circuit may generallybe any circuit for transmitting and/or receiving data. In one aspect,for example, the second data circuit may store information pertaining tothe particular surgical instrument with which it is associated. Suchinformation may include, for example, a model number, a serial number, anumber of operations in which the surgical instrument has been used,and/or any other type of information. Additionally or alternatively, anytype of information may be communicated to the second data circuit forstorage therein via the second data circuit interface 2100 (e.g., usingthe programmable logic device 2000). Such information may comprise, forexample, an updated number of operations in which the instrument hasbeen used and/or dates and/or times of its usage. In certain aspects,the second data circuit may transmit data acquired by one or moresensors (e.g., an instrument-based temperature sensor). In certainaspects, the second data circuit may receive data from the generator1100 and provide an indication to a user (e.g., an LED indication orother visible indication) based on the received data.

In certain aspects, the second data circuit and the second data circuitinterface 2100 may be configured such that communication between theprogrammable logic device 2000 and the second data circuit can beeffected without the need to provide additional conductors for thispurpose (e.g., dedicated conductors of a cable connecting a handpiece tothe generator 1100). In one aspect, for example, information may becommunicated to and from the second data circuit using a one-wire buscommunication scheme implemented on existing cabling, such as one of theconductors used transmit interrogation signals from the signalconditioning circuit 2020 to a control circuit in a handpiece. In thisway, design changes or modifications to the surgical device that mightotherwise be necessary are minimized or reduced. Moreover, becausedifferent types of communications can be implemented over a commonphysical channel (either with or without frequency-band separation), thepresence of a second data circuit may be “invisible” to generators thatdo not have the requisite data reading functionality, thus enablingbackward compatibility of the surgical device instrument.

In certain aspects, the isolated stage 1520 may comprise at least oneblocking capacitor 2960-1 (FIG. 8C) connected to the drive signal output1600 b to prevent passage of DC current to a patient. A single blockingcapacitor may be required to comply with medical regulations orstandards, for example. While failure in single-capacitor designs isrelatively uncommon, such failure may nonetheless have negativeconsequences. In one aspect, a second blocking capacitor 2960-2 may beprovided in series with the blocking capacitor 2960-1, with currentleakage from a point between the blocking capacitors 2960-1, 2960-2being monitored by, for example, an ADC 2980 for sampling a voltageinduced by leakage current. The samples may be received by theprogrammable logic device 2000, for example. Based on changes in theleakage current (as indicated by the voltage samples in the aspect ofFIG. 7), the generator 1100 may determine when at least one of theblocking capacitors 2960-1, 2960-2 has failed. Accordingly, the aspectof FIG. 7 may provide a benefit over single-capacitor designs having asingle point of failure.

In certain aspects, the non-isolated stage 1540 may comprise a powersupply 2110 for outputting DC power at a suitable voltage and current.The power supply may comprise, for example, a 400 W power supply foroutputting a 48 VDC system voltage. As discussed above, the power supply2110 may further comprise one or more DC/DC voltage converters 2130 forreceiving the output of the power supply to generate DC outputs at thevoltages and currents required by the various components of thegenerator 1100. As discussed above in connection with the controller1960, one or more of the DC/DC voltage converters 2130 may receive aninput from the controller 1960 when activation of the “on/off” inputdevice 2150 by a user is detected by the controller 1960 to enableoperation of, or wake, the DC/DC voltage converters 2130.

FIGS. 9A-9B illustrate certain functional and structural aspects of oneaspect of the generator 1100. Feedback indicating current and voltageoutput from the secondary winding 1580 of the power transformer 1560 isreceived by the ADCs 1780, 1800, respectively. As shown, the ADCs 1780,1800 may be implemented as a 2-channel ADC and may sample the feedbacksignals at a high speed (e.g., 80 Msps) to enable oversampling (e.g.,approximately 200× oversampling) of the drive signals. The current andvoltage feedback signals may be suitably conditioned in the analogdomain (e.g., amplified, filtered) prior to processing by the ADCs 1780,1800. Current and voltage feedback samples from the ADCs 1780, 1800 maybe individually buffered and subsequently multiplexed or interleavedinto a single data stream within block 2120 of the programmable logicdevice 1660. In the aspect of FIGS. 9A-9B, the programmable logic device1660 comprises an FPGA.

The multiplexed current and voltage feedback samples may be received bya parallel data acquisition port (PDAP) implemented within block 2144 ofthe processor 1740. The PDAP may comprise a packing unit forimplementing any of a number of methodologies for correlating themultiplexed feedback samples with a memory address. In one aspect, forexample, feedback samples corresponding to a particular LUT sampleoutput by the programmable logic device 1660 may be stored at one ormore memory addresses that are correlated or indexed with the LUTaddress of the LUT sample. In another aspect, feedback samplescorresponding to a particular LUT sample output by the programmablelogic device 1660 may be stored, along with the LUT address of the LUTsample, at a common memory location. In any event, the feedback samplesmay be stored such that the address of the LUT sample from which aparticular set of feedback samples originated may be subsequentlyascertained. As discussed above, synchronization of the LUT sampleaddresses and the feedback samples in this way contributes to thecorrect timing and stability of the pre-distortion algorithm. A directmemory access (DMA) controller implemented at block 2166 of theprocessor 1740 may store the feedback samples (and any LUT sampleaddress data, where applicable) at a designated memory location 2180 ofthe processor 1740 (e.g., internal RAM).

Block 2200 of the processor 1740 may implement a pre-distortionalgorithm for pre-distorting or modifying the LUT samples stored in theprogrammable logic device 1660 on a dynamic, ongoing basis. As discussedabove, pre-distortion of the LUT samples may compensate for varioussources of distortion present in the output drive circuit of thegenerator 1100. The pre-distorted LUT samples, when processed throughthe drive circuit, will therefore result in a drive signal having thedesired waveform shape (e.g., sinusoidal) for optimally driving theultrasonic transducer.

At block 2220 of the pre-distortion algorithm, the current through themotional branch of the ultrasonic transducer is determined. The motionalbranch current may be determined using Kirchhoff's Current Law based on,for example, the current and voltage feedback samples stored at memorylocation 2180 (which, when suitably scaled, may be representative ofI_(g) and V_(g) in the model of FIG. 6 discussed above), a value of theultrasonic transducer static capacitance C₀ (measured or known a priori)and a known value of the drive frequency. A motional branch currentsample for each set of stored current and voltage feedback samplesassociated with a LUT sample may be determined.

At block 2240 of the pre-distortion algorithm, each motional branchcurrent sample determined at block 2220 is compared to a sample of adesired current waveform shape to determine a difference, or sampleamplitude error, between the compared samples. For this determination,the sample of the desired current waveform shape may be supplied, forexample, from a waveform shape LUT 2260 containing amplitude samples forone cycle of a desired current waveform shape. The particular sample ofthe desired current waveform shape from the LUT 2260 used for thecomparison may be dictated by the LUT sample address associated with themotional branch current sample used in the comparison. Accordingly, theinput of the motional branch current to block 2240 may be synchronizedwith the input of its associated LUT sample address to block 2240. TheLUT samples stored in the programmable logic device 1660 and the LUTsamples stored in the waveform shape LUT 2260 may therefore be equal innumber. In certain aspects, the desired current waveform shaperepresented by the LUT samples stored in the waveform shape LUT 2260 maybe a fundamental sine wave. Other waveform shapes may be desirable. Forexample, it is contemplated that a fundamental sine wave for drivingmain longitudinal motion of an ultrasonic transducer superimposed withone or more other drive signals at other frequencies, such as a thirdorder harmonic for driving at least two mechanical resonances forbeneficial vibrations of transverse or other modes, could be used.

Each value of the sample amplitude error determined at block 2240 may betransmitted to the LUT of the programmable logic device 1660 (shown atblock 2280 in FIG. 9A) along with an indication of its associated LUTaddress. Based on the value of the sample amplitude error and itsassociated address (and, optionally, values of sample amplitude errorfor the same LUT address previously received), the LUT 2280 (or othercontrol block of the programmable logic device 1660) may pre-distort ormodify the value of the LUT sample stored at the LUT address such thatthe sample amplitude error is reduced or minimized. It will beappreciated that such pre-distortion or modification of each LUT samplein an iterative manner across the entire range of LUT addresses willcause the waveform shape of the generator's output current to match orconform to the desired current waveform shape represented by the samplesof the waveform shape LUT 2260.

Current and voltage amplitude measurements, power measurements andimpedance measurements may be determined at block 2300 of the processor1740 based on the current and voltage feedback samples stored at memorylocation 2180. Prior to the determination of these quantities, thefeedback samples may be suitably scaled and, in certain aspects,processed through a suitable filter 2320 to remove noise resulting from,for example, the data acquisition process and induced harmoniccomponents. The filtered voltage and current samples may thereforesubstantially represent the fundamental frequency of the generator'sdrive output signal. In certain aspects, the filter 2320 may be a finiteimpulse response (FIR) filter applied in the frequency domain. Suchaspects may use the Fast Fourier Transform (FFT) of the output drivesignal current and voltage signals. In certain aspects, the resultingfrequency spectrum may be used to provide additional generatorfunctionality. In one aspect, for example, the ratio of the secondand/or third order harmonic component relative to the fundamentalfrequency component may be used as a diagnostic indicator.

At block 2340 (FIG. 9B), a root mean square (RMS) calculation may beapplied to a sample size of the current feedback samples representing anintegral number of cycles of the drive signal to generate a measurementI_(rms) representing the drive signal output current.

At block 2360, a root mean square (RMS) calculation may be applied to asample size of the voltage feedback samples representing an integralnumber of cycles of the drive signal to determine a measurement V_(rms)representing the drive signal output voltage.

At block 2380, the current and voltage feedback samples may bemultiplied point by point, and a mean calculation is applied to samplesrepresenting an integral number of cycles of the drive signal todetermine a measurement P, of the generator's real output power.

At block 2400, measurement P_(a) of the generator's apparent outputpower may be determined as the product V_(rms)·I_(rms).

At block 2420, measurement Z_(m) of the load impedance magnitude may bedetermined as the quotient V_(rms)/I_(rms).

In certain aspects, the quantities I_(rms), V_(rms), P_(r), P_(a) andZ_(m) determined at blocks 2340, 2360, 2380, 2400 and 2420 may be usedby the generator 1100 to implement any of a number of control and/ordiagnostic processes. In certain aspects, any of these quantities may becommunicated to a user via, for example, an output device 2140 integralwith the generator 1100 or an output device 2140 connected to thegenerator 1100 through a suitable communication interface (e.g., a USBinterface). Various diagnostic processes may include, withoutlimitation, handpiece integrity, instrument integrity, instrumentattachment integrity, instrument overload, approaching instrumentoverload, frequency lock failure, over-voltage condition, over-currentcondition, over-power condition, voltage sense failure, current sensefailure, audio indication failure, visual indication failure, shortcircuit condition, power delivery failure, or blocking capacitorfailure, for example.

Block 2440 of the processor 1740 may implement a phase control algorithmfor determining and controlling the impedance phase of an electricalload (e.g., the ultrasonic transducer) driven by the generator 1100. Asdiscussed above, by controlling the frequency of the drive signal tominimize or reduce the difference between the determined impedance phaseand an impedance phase setpoint (e.g., 0°), the effects of harmonicdistortion may be minimized or reduced, and the accuracy of the phasemeasurement increased.

The phase control algorithm receives as input the current and voltagefeedback samples stored in the memory location 2180. Prior to their usein the phase control algorithm, the feedback samples may be suitablyscaled and, in certain aspects, processed through a suitable filter 2460(which may be identical to filter 2320) to remove noise resulting fromthe data acquisition process and induced harmonic components, forexample. The filtered voltage and current samples may thereforesubstantially represent the fundamental frequency of the generator'sdrive output signal.

At block 2480 of the phase control algorithm, the current through themotional branch of the ultrasonic transducer is determined. Thisdetermination may be identical to that described above in connectionwith block 2220 of the pre-distortion algorithm. The output of block2480 may thus be, for each set of stored current and voltage feedbacksamples associated with a LUT sample, a motional branch current sample.

At block 2500 of the phase control algorithm, impedance phase isdetermined based on the synchronized input of motional branch currentsamples determined at block 2480 and corresponding voltage feedbacksamples. In certain aspects, the impedance phase is determined as theaverage of the impedance phase measured at the rising edge of thewaveforms and the impedance phase measured at the falling edge of thewaveforms.

At block 2520 of the of the phase control algorithm, the value of theimpedance phase determined at block 2220 is compared to phase setpoint2540 to determine a difference, or phase error, between the comparedvalues.

At block 2560 (FIG. 9A) of the phase control algorithm, based on a valueof phase error determined at block 2520 and the impedance magnitudedetermined at block 2420, a frequency output for controlling thefrequency of the drive signal is determined. The value of the frequencyoutput may be continuously adjusted by the block 2560 and transferred toa DDS control block 2680 (discussed below) in order to maintain theimpedance phase determined at block 2500 at the phase setpoint (e.g.,zero phase error). In certain aspects, the impedance phase may beregulated to a 0° phase setpoint. In this way, any harmonic distortionwill be centered about the crest of the voltage waveform, enhancing theaccuracy of phase impedance determination.

Block 2580 of the processor 1740 may implement an algorithm formodulating the current amplitude of the drive signal in order to controlthe drive signal current, voltage and power in accordance with userspecified setpoints, or in accordance with requirements specified byother processes or algorithms implemented by the generator 1100. Controlof these quantities may be realized, for example, by scaling the LUTsamples in the LUT 2280 and/or by adjusting the full-scale outputvoltage of the DAC 1680 (which supplies the input to the power amplifier1620) via a DAC 1860. Block 2600 (which may be implemented as a PIDcontroller in certain aspects) may receive, as input, current feedbacksamples (which may be suitably scaled and filtered) from the memorylocation 2180. The current feedback samples may be compared to a“current demand” I_(d) value dictated by the controlled variable (e.g.,current, voltage or power) to determine if the drive signal is supplyingthe necessary current. In aspects in which drive signal current is thecontrol variable, the current demand I_(d) may be specified directly bya current setpoint 2620A (I_(sp)). For example, an RMS value of thecurrent feedback data (determined as in block 2340) may be compared touser-specified RMS current setpoint I_(sp) to determine the appropriatecontroller action. If, for example, the current feedback data indicatesan RMS value less than the current setpoint I_(sp), LUT scaling and/orthe full-scale output voltage of the DAC 1680 may be adjusted by theblock 2600 such that the drive signal current is increased. Conversely,block 2600 may adjust LUT scaling and/or the full-scale output voltageof the DAC 1680 to decrease the drive signal current when the currentfeedback data indicates an RMS value greater than the current setpointI_(sp).

In aspects in which the drive signal voltage is the control variable,the current demand I_(d) may be specified indirectly, for example, basedon the current required to maintain a desired voltage setpoint 2620B(V_(sp)) given the load impedance magnitude Z_(m) measured at block 2420(e.g. I_(d)=V_(sp)/Z_(m)). Similarly, in aspects in which drive signalpower is the control variable, the current demand I_(d) may be specifiedindirectly, for example, based on the current required to maintain adesired power setpoint 2620C (P_(sp)) given the voltage V_(rms) measuredat blocks 2360 (e.g. I_(d)=P_(sp)/V_(rms)).

Block 2680 (FIG. 9A) may implement a DDS control algorithm forcontrolling the drive signal by recalling LUT samples stored in the LUT2280. In certain aspects, the DDS control algorithm may be anumerically-controlled oscillator (NCO) algorithm for generating samplesof a waveform at a fixed clock rate using a point (memorylocation)-skipping technique. The NCO algorithm may implement a phaseaccumulator, or frequency-to-phase converter, that functions as anaddress pointer for recalling LUT samples from the LUT 2280. In oneaspect, the phase accumulator may be a D step size, modulo N phaseaccumulator, where D is a positive integer representing a frequencycontrol value, and N is the number of LUT samples in the LUT 2280. Afrequency control value of D=1, for example, may cause the phaseaccumulator to sequentially point to every address of the LUT 2280,resulting in a waveform output replicating the waveform stored in theLUT 2280. When D>1, the phase accumulator may skip addresses in the LUT2280, resulting in a waveform output having a higher frequency.Accordingly, the frequency of the waveform generated by the DDS controlalgorithm may therefore be controlled by suitably varying the frequencycontrol value. In certain aspects, the frequency control value may bedetermined based on the output of the phase control algorithmimplemented at block 2440. The output of block 2680 may supply the inputof DAC 1680, which in turn supplies a corresponding analog signal to aninput of the power amplifier 1620.

Block 2700 of the processor 1740 may implement a switch-mode convertercontrol algorithm for dynamically modulating the rail voltage of thepower amplifier 1620 based on the waveform envelope of the signal beingamplified, thereby improving the efficiency of the power amplifier 1620.In certain aspects, characteristics of the waveform envelope may bedetermined by monitoring one or more signals contained in the poweramplifier 1620. In one aspect, for example, characteristics of thewaveform envelope may be determined by monitoring the minima of a drainvoltage (e.g., a MOSFET drain voltage) that is modulated in accordancewith the envelope of the amplified signal. A minima voltage signal maybe generated, for example, by a voltage minima detector coupled to thedrain voltage. The minima voltage signal may be sampled by ADC 1760,with the output minima voltage samples being received at block 2720 ofthe switch-mode converter control algorithm. Based on the values of theminima voltage samples, block 2740 may control a PWM signal output by aPWM generator 2760, which, in turn, controls the rail voltage suppliedto the power amplifier 1620 by the switch-mode regulator 1700. Incertain aspects, as long as the values of the minima voltage samples areless than a minima target 2780 input into block 2720, the rail voltagemay be modulated in accordance with the waveform envelope ascharacterized by the minima voltage samples. When the minima voltagesamples indicate low envelope power levels, for example, block 2740 maycause a low rail voltage to be supplied to the power amplifier 1620,with the full rail voltage being supplied only when the minima voltagesamples indicate maximum envelope power levels. When the minima voltagesamples fall below the minima target 2780, block 2740 may cause the railvoltage to be maintained at a minimum value suitable for ensuring properoperation of the power amplifier 1620.

FIG. 10 illustrates a control circuit 500 configured to control aspectsof the surgical instrument or tool according to one aspect of thisdisclosure. The control circuit 500 can be configured to implementvarious processes described herein. The control circuit 500 may comprisea microcontroller comprising one or more processors 502 (e.g.,microprocessor, microcontroller) coupled to at least one memory circuit504. The memory circuit 504 stores machine-executable instructions that,when executed by the processor 502, cause the processor 502 to executemachine instructions to implement various processes described herein.The processor 502 may be any one of a number of single-core or multicoreprocessors known in the art. The memory circuit 504 may comprisevolatile and non-volatile storage media. The processor 502 may includean instruction processing unit 506 and an arithmetic unit 508. Theinstruction processing unit may be configured to receive instructionsfrom the memory circuit 504 of this disclosure.

FIG. 11 illustrates a combinational logic circuit 510 configured tocontrol aspects of the surgical instrument or tool according to oneaspect of this disclosure. The combinational logic circuit 510 can beconfigured to implement various processes described herein. Thecombinational logic circuit 510 may comprise a finite state machinecomprising a combinational logic 512 configured to receive dataassociated with the surgical instrument or tool at an input 514, processthe data by the combinational logic 512, and provide an output 516.

FIG. 12 illustrates a sequential logic circuit 520 configured to controlaspects of the surgical instrument or tool according to one aspect ofthis disclosure. The sequential logic circuit 520 or the combinationallogic 522 can be configured to implement various processes describedherein. The sequential logic circuit 520 may comprise a finite statemachine. The sequential logic circuit 520 may comprise a combinationallogic 522, at least one memory circuit 524, and a clock 529, forexample. The at least one memory circuit 524 can store a current stateof the finite state machine. In certain instances, the sequential logiccircuit 520 may be synchronous or asynchronous. The combinational logic522 is configured to receive data associated with the surgicalinstrument or tool from an input 526, process the data by thecombinational logic 522, and provide an output 528. In other aspects,the circuit may comprise a combination of a processor (e.g., processor502, FIG. 13) and a finite state machine to implement various processesherein. In other aspects, the finite state machine may comprise acombination of a combinational logic circuit (e.g., combinational logiccircuit 510, FIG. 14) and the sequential logic circuit 520.

In one aspect, the ultrasonic or high-frequency current generators ofthe surgical system 1000 may be configured to generate the electricalsignal waveform digitally such that the desired using a predeterminednumber of phase points stored in a lookup table to digitize the waveshape. The phase points may be stored in a table defined in a memory, afield programmable gate array (FPGA), or any suitable non-volatilememory. FIG. 13 illustrates one aspect of a fundamental architecture fora digital synthesis circuit such as a direct digital synthesis (DDS)circuit 4100 configured to generate a plurality of wave shapes for theelectrical signal waveform. The generator software and digital controlsmay command the FPGA to scan the addresses in the lookup table 4104which in turn provides varying digital input values to a DAC circuit4108 that feeds a power amplifier. The addresses may be scannedaccording to a frequency of interest. Using such a lookup table 4104enables generating various types of wave shapes that can be fed intotissue or into a transducer, an RF electrode, multiple transducerssimultaneously, multiple RF electrodes simultaneously, or a combinationof RF and ultrasonic instruments. Furthermore, multiple lookup tables4104 that represent multiple wave shapes can be created, stored, andapplied to tissue from a generator.

The waveform signal may be configured to control at least one of anoutput current, an output voltage, or an output power of an ultrasonictransducer and/or an RF electrode, or multiples thereof (e.g. two ormore ultrasonic transducers and/or two or more RF electrodes). Further,where the surgical instrument comprises an ultrasonic components, thewaveform signal may be configured to drive at least two vibration modesof an ultrasonic transducer of the at least one surgical instrument.Accordingly, a generator may be configured to provide a waveform signalto at least one surgical instrument wherein the waveform signalcorresponds to at least one wave shape of a plurality of wave shapes ina table. Further, the waveform signal provided to the two surgicalinstruments may comprise two or more wave shapes. The table may compriseinformation associated with a plurality of wave shapes and the table maybe stored within the generator. In one aspect or example, the table maybe a direct digital synthesis table, which may be stored in an FPGA ofthe generator. The table may be addressed by anyway that is convenientfor categorizing wave shapes. According to one aspect, the table, whichmay be a direct digital synthesis table, is addressed according to afrequency of the waveform signal. Additionally, the informationassociated with the plurality of wave shapes may be stored as digitalinformation in the table.

The analog electrical signal waveform may be configured to control atleast one of an output current, an output voltage, or an output power ofan ultrasonic transducer and/or an RF electrode, or multiples thereof(e.g., two or more ultrasonic transducers and/or two or more RFelectrodes). Further, where the surgical instrument comprises ultrasoniccomponents, the analog electrical signal waveform may be configured todrive at least two vibration modes of an ultrasonic transducer of the atleast one surgical instrument. Accordingly, the generator circuit may beconfigured to provide an analog electrical signal waveform to at leastone surgical instrument wherein the analog electrical signal waveformcorresponds to at least one wave shape of a plurality of wave shapesstored in a lookup table 4104. Further, the analog electrical signalwaveform provided to the two surgical instruments may comprise two ormore wave shapes. The lookup table 4104 may comprise informationassociated with a plurality of wave shapes and the lookup table 4104 maybe stored either within the generator circuit or the surgicalinstrument. In one aspect or example, the lookup table 4104 may be adirect digital synthesis table, which may be stored in an FPGA of thegenerator circuit or the surgical instrument. The lookup table 4104 maybe addressed by anyway that is convenient for categorizing wave shapes.According to one aspect, the lookup table 4104, which may be a directdigital synthesis table, is addressed according to a frequency of thedesired analog electrical signal waveform. Additionally, the informationassociated with the plurality of wave shapes may be stored as digitalinformation in the lookup table 4104.

With the widespread use of digital techniques in instrumentation andcommunications systems, a digitally-controlled method of generatingmultiple frequencies from a reference frequency source has evolved andis referred to as direct digital synthesis. The basic architecture isshown in FIG. 13. In this simplified block diagram, a DDS circuit iscoupled to a processor, controller, or a logic device of the generatorcircuit and to a memory circuit located in the generator circuit of thesurgical system 1000. The DDS circuit 4100 comprises an address counter4102, lookup table 4104, a register 4106, a DAC circuit 4108, and afilter 4112. A stable clock f_(c) is received by the address counter4102 and the register 4106 drives a programmable-read-only-memory (PROM)which stores one or more integral number of cycles of a sinewave (orother arbitrary waveform) in a lookup table 4104. As the address counter4102 steps through memory locations, values stored in the lookup table4104 are written to the register 4106, which is coupled to the DACcircuit 4108. The corresponding digital amplitude of the signal at thememory location of the lookup table 4104 drives the DAC circuit 4108,which in turn generates an analog output signal 4110. The spectralpurity of the analog output signal 4110 is determined primarily by theDAC circuit 4108. The phase noise is basically that of the referenceclock f_(c). The first analog output signal 4110 output from the DACcircuit 4108 is filtered by the filter 4112 and a second analog outputsignal 4114 output by the filter 4112 is provided to an amplifier havingan output coupled to the output of the generator circuit. The secondanalog output signal has a frequency f_(out).

Because the DDS circuit 4100 is a sampled data system, issues involvedin sampling must be considered: quantization noise, aliasing, filtering,etc. For instance, the higher order harmonics of the DAC circuit 4108output frequencies fold back into the Nyquist bandwidth, making themunfilterable, whereas, the higher order harmonics of the output ofphase-locked-loop (PLL) based synthesizers can be filtered. The lookuptable 4104 contains signal data for an integral number of cycles. Thefinal output frequency f_(out) can be changed changing the referenceclock frequency f_(c) or by reprogramming the PROM.

The DDS circuit 4100 may comprise multiple lookup tables 4104 where thelookup table 4104 stores a waveform represented by a predeterminednumber of samples, wherein the samples define a predetermined shape ofthe waveform. Thus multiple waveforms having a unique shape can bestored in multiple lookup tables 4104 to provide different tissuetreatments based on instrument settings or tissue feedback. Examples ofwaveforms include high crest factor RF electrical signal waveforms forsurface tissue coagulation, low crest factor RF electrical signalwaveform for deeper tissue penetration, and electrical signal waveformsthat promote efficient touch-up coagulation. In one aspect, the DDScircuit 4100 can create multiple wave shape lookup tables 4104 andduring a tissue treatment procedure (e.g., “on-the-fly” or in virtualreal time based on user or sensor inputs) switch between different waveshapes stored in separate lookup tables 4104 based on the tissue effectdesired and/or tissue feedback. Accordingly, switching between waveshapes can be based on tissue impedance and other factors, for example.In other aspects, the lookup tables 4104 can store electrical signalwaveforms shaped to maximize the power delivered into the tissue percycle (i.e., trapezoidal or square wave). In other aspects, the lookuptables 4104 can store wave shapes synchronized in such way that theymake maximizing power delivery by the multifunction surgical instrumentof surgical system 1000 while delivering RF and ultrasonic drivesignals. In yet other aspects, the lookup tables 4104 can storeelectrical signal waveforms to drive ultrasonic and RF therapeutic,and/or sub-therapeutic, energy simultaneously while maintainingultrasonic frequency lock. Custom wave shapes specific to differentinstruments and their tissue effects can be stored in the non-volatilememory of the generator circuit or in the non-volatile memory (e.g.,EEPROM) of the surgical system 1000 and be fetched upon connecting themultifunction surgical instrument to the generator circuit. An exampleof an exponentially damped sinusoid, as used in many high crest factor“coagulation” waveforms is shown in FIG. 15.

A more flexible and efficient implementation of the DDS circuit 4100employs a digital circuit called a Numerically Controlled Oscillator(NCO). A block diagram of a more flexible and efficient digitalsynthesis circuit such as a DDS circuit 4200 is shown in FIG. 14. Inthis simplified block diagram, a DDS circuit 4200 is coupled to aprocessor, controller, or a logic device of the generator and to amemory circuit located either in the generator or in any of the surgicalinstruments of surgical system 1000. The DDS circuit 4200 comprises aload register 4202, a parallel delta phase register 4204, an addercircuit 4216, a phase register 4208, a lookup table 4210(phase-to-amplitude converter), a DAC circuit 4212, and a filter 4214.The adder circuit 4216 and the phase register 4208 form part of a phaseaccumulator 4206. A clock frequency f_(c) is applied to the phaseregister 4208 and a DAC circuit 4212. The load register 4202 receives atuning word that specifies output frequency as a fraction of thereference clock frequency signal f_(c). The output of the load register4202 is provided to the parallel delta phase register 4204 with a tuningword M.

The DDS circuit 4200 includes a sample clock that generates the clockfrequency f_(c), the phase accumulator 4206, and the lookup table 4210(e.g., phase to amplitude converter). The content of the phaseaccumulator 4206 is updated once per clock cycle f_(c). When time thephase accumulator 4206 is updated, the digital number, M, stored in theparallel delta phase register 4204 is added to the number in the phaseregister 4208 by the adder circuit 4216. Assuming that the number in theparallel delta phase register 4204 is 00 . . . 01 and that the initialcontents of the phase accumulator 4206 is 00 . . . 00. The phaseaccumulator 4206 is updated by 00 . . . 01 per clock cycle. If the phaseaccumulator 4206 is 32-bits wide, 232 clock cycles (over 4 billion) arerequired before the phase accumulator 4206 returns to 00 . . . 00, andthe cycle repeats.

A truncated output 4218 of the phase accumulator 4206 is provided to aphase-to amplitude converter lookup table 4210 and the output of thelookup table 4210 is coupled to a DAC circuit 4212. The truncated output4218 of the phase accumulator 4206 serves as the address to a sine (orcosine) lookup table. An address in the lookup table corresponds to aphase point on the sinewave from 0° to 360°. The lookup table 4210contains the corresponding digital amplitude information for onecomplete cycle of a sinewave. The lookup table 4210 therefore maps thephase information from the phase accumulator 4206 into a digitalamplitude word, which in turn drives the DAC circuit 4212. The output ofthe DAC circuit is a first analog signal 4220 and is filtered by afilter 4214. The output of the filter 4214 is a second analog signal4222, which is provided to a power amplifier coupled to the output ofthe generator circuit.

In one aspect, the electrical signal waveform may be digitized into 1024(210) phase points, although the wave shape may be digitized is anysuitable number of 2n phase points ranging from 256 (28) to281,474,976,710,656 (248), where n is a positive integer, as shown inTABLE 1. The electrical signal waveform may be expressed asA_(n)(θ_(n)), where a normalized amplitude A_(n) at a point n isrepresented by a phase angle θ_(n) is referred to as a phase point atpoint n. The number of discrete phase points n determines the tuningresolution of the DDS circuit 4200 (as well as the DDS circuit 4100shown in FIG. 13).

TABLE 1 specifies the electrical signal waveform digitized into a numberof phase points.

TABLE 1 N Number of Phase Points 2^(n)  8 256 10 1,024 12 4,096 1416,384 16 65,536 18 262,144 20 1,048,576 22 4,194,304 24 16,777,216 2667,108,864 28 268,435,456 . . . . . . 32 4,294,967,296 . . . . . . 48281,474,976,710,656 . . . . . .

The generator circuit algorithms and digital control circuits scan theaddresses in the lookup table 4210, which in turn provides varyingdigital input values to the DAC circuit 4212 that feeds the filter 4214and the power amplifier. The addresses may be scanned according to afrequency of interest. Using the lookup table enables generating varioustypes of shapes that can be converted into an analog output signal bythe DAC circuit 4212, filtered by the filter 4214, amplified by thepower amplifier coupled to the output of the generator circuit, and fedto the tissue in the form of RF energy or fed to an ultrasonictransducer and applied to the tissue in the form of ultrasonicvibrations which deliver energy to the tissue in the form of heat. Theoutput of the amplifier can be applied to an RF electrode, multiple RFelectrodes simultaneously, an ultrasonic transducer, multiple ultrasonictransducers simultaneously, or a combination of RF and ultrasonictransducers, for example. Furthermore, multiple wave shape tables can becreated, stored, and applied to tissue from a generator circuit.

With reference back to FIG. 13, for n=32, and M=1, the phase accumulator4206 steps through 232 possible outputs before it overflows andrestarts. The corresponding output wave frequency is equal to the inputclock frequency divided by 232. If M=2, then the phase register 1708“rolls over” twice as fast, and the output frequency is doubled. Thiscan be generalized as follows.

For a phase accumulator 4206 configured to accumulate n-bits (ngenerally ranges from 24 to 32 in most DDS systems, but as previouslydiscussed n may be selected from a wide range of options), there are2^(n) possible phase points. The digital word in the delta phaseregister, M, represents the amount the phase accumulator is incrementedper clock cycle. If f_(c) is the clock frequency, then the frequency ofthe output sinewave is equal to:

$f_{0} = \frac{M \cdot f_{c}}{2^{n}}$

The above equation is known as the DDS “tuning equation.” Note that thefrequency resolution of the system is equal to

$\frac{f_{0}}{2^{n}}.$

For n=32, the resolution is greater than one part in four billion. Inone aspect of the DDS circuit 4200, not all of the bits out of the phaseaccumulator 4206 are passed on to the lookup table 4210, but aretruncated, leaving only the first 13 to 15 most significant bits (MSBs),for example. This reduces the size of the lookup table 4210 and does notaffect the frequency resolution. The phase truncation only adds a smallbut acceptable amount of phase noise to the final output.

The electrical signal waveform may be characterized by a current,voltage, or power at a predetermined frequency. Further, where any oneof the surgical instruments of surgical system 1000 comprises ultrasoniccomponents, the electrical signal waveform may be configured to drive atleast two vibration modes of an ultrasonic transducer of the at leastone surgical instrument. Accordingly, the generator circuit may beconfigured to provide an electrical signal waveform to at least onesurgical instrument wherein the electrical signal waveform ischaracterized by a predetermined wave shape stored in the lookup table4210 (or lookup table 4104 FIG. 13). Further, the electrical signalwaveform may be a combination of two or more wave shapes. The lookuptable 4210 may comprise information associated with a plurality of waveshapes. In one aspect or example, the lookup table 4210 may be generatedby the DDS circuit 4200 and may be referred to as a direct digitalsynthesis table. DDS works by first storing a large repetitive waveformin onboard memory. A cycle of a waveform (sine, triangle, square,arbitrary) can be represented by a predetermined number of phase pointsas shown in TABLE 1 and stored into memory. Once the waveform is storedinto memory, it can be generated at very precise frequencies. The directdigital synthesis table may be stored in a non-volatile memory of thegenerator circuit and/or may be implemented with a FPGA circuit in thegenerator circuit. The lookup table 4210 may be addressed by anysuitable technique that is convenient for categorizing wave shapes.According to one aspect, the lookup table 4210 is addressed according toa frequency of the electrical signal waveform. Additionally, theinformation associated with the plurality of wave shapes may be storedas digital information in a memory or as part of the lookup table 4210.

In one aspect, the generator circuit may be configured to provideelectrical signal waveforms to at least two surgical instrumentssimultaneously. The generator circuit also may be configured to providethe electrical signal waveform, which may be characterized two or morewave shapes, via an output channel of the generator circuit to the twosurgical instruments simultaneously. For example, in one aspect theelectrical signal waveform comprises a first electrical signal to drivean ultrasonic transducer (e.g., ultrasonic drive signal), a second RFdrive signal, and/or a combination thereof. In addition, an electricalsignal waveform may comprise a plurality of ultrasonic drive signals, aplurality of RF drive signals, and/or a combination of a plurality ofultrasonic and RF drive signals.

In addition, a method of operating the generator circuit according tothe present disclosure comprises generating an electrical signalwaveform and providing the generated electrical signal waveform to anyone of the surgical instruments of surgical system 1000, wheregenerating the electrical signal waveform comprises receivinginformation associated with the electrical signal waveform from amemory. The generated electrical signal waveform comprises at least onewave shape. Furthermore, providing the generated electrical signalwaveform to the at least one surgical instrument comprises providing theelectrical signal waveform to at least two surgical instrumentssimultaneously.

The generator circuit as described herein may allow for the generationof various types of direct digital synthesis tables. Examples of waveshapes for RF/Electrosurgery signals suitable for treating a variety oftissue generated by the generator circuit include RF signals with a highcrest factor (which may be used for surface coagulation in RF mode), alow crest factor RF signals (which may be used for deeper tissuepenetration), and waveforms that promote efficient touch-up coagulation.The generator circuit also may generate multiple wave shapes employing adirect digital synthesis lookup table 4210 and, on the fly, can switchbetween particular wave shapes based on the desired tissue effect.Switching may be based on tissue impedance and/or other factors.

In addition to traditional sine/cosine wave shapes, the generatorcircuit may be configured to generate wave shape(s) that maximize thepower into tissue per cycle (i.e., trapezoidal or square wave). Thegenerator circuit may provide wave shape(s) that are synchronized tomaximize the power delivered to the load when driving RF and ultrasonicsignals simultaneously and to maintain ultrasonic frequency lock,provided that the generator circuit includes a circuit topology thatenables simultaneously driving RF and ultrasonic signals. Further,custom wave shapes specific to instruments and their tissue effects canbe stored in a non-volatile memory (NVM) or an instrument EEPROM and canbe fetched upon connecting any one of the surgical instruments ofsurgical system 1000 to the generator circuit.

The DDS circuit 4200 may comprise multiple lookup tables 4104 where thelookup table 4210 stores a waveform represented by a predeterminednumber of phase points (also may be referred to as samples), wherein thephase points define a predetermined shape of the waveform. Thus multiplewaveforms having a unique shape can be stored in multiple lookup tables4210 to provide different tissue treatments based on instrument settingsor tissue feedback. Examples of waveforms include high crest factor RFelectrical signal waveforms for surface tissue coagulation, low crestfactor RF electrical signal waveform for deeper tissue penetration, andelectrical signal waveforms that promote efficient touch-up coagulation.In one aspect, the DDS circuit 4200 can create multiple wave shapelookup tables 4210 and during a tissue treatment procedure (e.g.,“on-the-fly” or in virtual real time based on user or sensor inputs)switch between different wave shapes stored in different lookup tables4210 based on the tissue effect desired and/or tissue feedback.Accordingly, switching between wave shapes can be based on tissueimpedance and other factors, for example. In other aspects, the lookuptables 4210 can store electrical signal waveforms shaped to maximize thepower delivered into the tissue per cycle (i.e., trapezoidal or squarewave). In other aspects, the lookup tables 4210 can store wave shapessynchronized in such way that they make maximizing power delivery by anyone of the surgical instruments of surgical system 1000 when deliveringRF and ultrasonic drive signals. In yet other aspects, the lookup tables4210 can store electrical signal waveforms to drive ultrasonic and RFtherapeutic, and/or sub-therapeutic, energy simultaneously whilemaintaining ultrasonic frequency lock. Generally, the output wave shapemay be in the form of a sine wave, cosine wave, pulse wave, square wave,and the like. Nevertheless, the more complex and custom wave shapesspecific to different instruments and their tissue effects can be storedin the non-volatile memory of the generator circuit or in thenon-volatile memory (e.g., EEPROM) of the surgical instrument and befetched upon connecting the surgical instrument to the generatorcircuit. One example of a custom wave shape is an exponentially dampedsinusoid as used in many high crest factor “coagulation” waveforms, asshown in FIG. 43.

FIG. 15 illustrates one cycle of a discrete time digital electricalsignal waveform 4300, in accordance with at least one aspect of thepresent disclosure of an analog waveform 4304 (shown superimposed overthe discrete time digital electrical signal waveform 4300 for comparisonpurposes). The horizontal axis represents Time (t) and the vertical axisrepresents digital phase points. The digital electrical signal waveform4300 is a digital discrete time version of the desired analog waveform4304, for example. The digital electrical signal waveform 4300 isgenerated by storing an amplitude phase point 4302 that represents theamplitude per clock cycle T_(clk) over one cycle or period T₀. Thedigital electrical signal waveform 4300 is generated over one period T₀by any suitable digital processing circuit. The amplitude phase pointsare digital words stored in a memory circuit. In the example illustratedin FIGS. 13, 14, the digital word is a six-bit word that is capable ofstoring the amplitude phase points with a resolution of 26 or 64 bits.It will be appreciated that the examples shown in FIGS. 13, 14 is forillustrative purposes and in actual implementations the resolution canbe much higher. The digital amplitude phase points 4302 over one cycleT₀ are stored in the memory as a string of string words in a lookuptable 4104, 4210 as described in connection with FIGS. 13, 14, forexample. To generate the analog version of the analog waveform 4304, theamplitude phase points 4302 are read sequentially from the memory from 0to T₀ per clock cycle T_(clk) and are converted by a DAC circuit 4108,4212, also described in connection with FIGS. 13, 14. Additional cyclescan be generated by repeatedly reading the amplitude phase points 4302of the digital electrical signal waveform 4300 the from 0 to T₀ for asmany cycles or periods as may be desired. The smooth analog version ofthe analog waveform 4304 is achieved by filtering the output of the DACcircuit 4108, 4212 by a filter 4112, 4214 (FIGS. 13 and 14). Thefiltered analog output signal 4114, 4222 (FIGS. 13 and 14) is applied tothe input of a power amplifier.

FIG. 16 is a diagram of a control system 12950 that may be implementedas a nested PID feedback controller. A PID controller is a control loopfeedback mechanism (controller) to continuously calculate an error valueas the difference between a desired set point and a measured processvariable and applies a correction based on proportional, integral, andderivative terms (sometimes denoted P, I, and D respectively). Thenested PID controller feedback control system 12950 includes a primarycontroller 12952, in a primary (outer) feedback loop 12954 and asecondary controller 12955 in a secondary (inner) feedback loop 12956.The primary controller 12952 may be a PID controller 12972 as shown inFIG. 17, and the secondary controller 12955 also may be a PID controller12972 as shown in FIG. 17. The primary controller 12952 controls aprimary process 12958 and the secondary controller 12955 controls asecondary process 12960. The output 12966 of the primary process 12958is subtracted from a primary set point SP₁ by a first summer 12962. Thefirst summer 12962 produces a single sum output signal which is appliedto the primary controller 12952. The output of the primary controller12952 is the secondary set point SP₂. The output 12968 of the secondaryprocess 12960 is subtracted from the secondary set point SP₂ by a secondsummer 12964.

FIG. 17 illustrates a PID feedback control system 12970 according to oneaspect of this disclosure. The primary controller 12952 or the secondarycontroller 12955, or both, may be implemented as a PID controller 12972.In one aspect, the PID controller 12972 may comprise a proportionalelement 12974 (P), an integral element 12976 (I), and a derivativeelement 12978 (D). The outputs of the P, I, D elements 12974, 12976,12978 are summed by a summer 12986, which provides the control variableμ(t) to the process 12980. The output of the process 12980 is theprocess variable y(t). A summer 12984 calculates the difference betweena desired set point r(t) and a measured process variable y(t). The PIDcontroller 12972 continuously calculates an error value e(t) (e.g.,difference between closure force threshold and measured closure force)as the difference between a desired set point r(t) (e.g., closure forcethreshold) and a measured process variable y(t) (e.g., velocity anddirection of closure tube) and applies a correction based on theproportional, integral, and derivative terms calculated by theproportional element 12974 (P), integral element 12976 (I), andderivative element 12978 (D), respectively. The PID controller 12972attempts to minimize the error e(t) over time by adjustment of thecontrol variable p(t) (e.g., velocity and direction of the closuretube).

In accordance with the PID algorithm, the “P” element 12974 accounts forpresent values of the error. For example, if the error is large andpositive, the control output will also be large and positive. Inaccordance with the present disclosure, the error term e(t) is thedifferent between the desired closure force and the measured closureforce of the closure tube. The “I” element 12976 accounts for pastvalues of the error. For example, if the current output is notsufficiently strong, the integral of the error will accumulate overtime, and the controller will respond by applying a stronger action. The“D” element 12978 accounts for possible future trends of the error,based on its current rate of change. For example, continuing the Pexample above, when the large positive control output succeeds inbringing the error closer to zero, it also puts the process on a path tolarge negative error in the near future. In this case, the derivativeturns negative and the D module reduces the strength of the action toprevent this overshoot.

It will be appreciated that other variables and set points may bemonitored and controlled in accordance with the feedback control systems12950, 12970. For example, the adaptive closure member velocity controlalgorithm described herein may measure at least two of the followingparameters: firing member stroke location, firing member load,displacement of cutting element, velocity of cutting element, closuretube stroke location, closure tube load, among others.

FIG. 18 is an alternative system 132000 for controlling the frequency ofan ultrasonic electromechanical system 132002 and detecting theimpedance thereof, in accordance with at least one aspect of the presentdisclosure. The system 132000 may be incorporated into a generator. Aprocessor 132004 coupled to a memory 132026 programs a programmablecounter 132006 to tune to the output frequency f₀ of the ultrasonicelectromechanical system 132002. The input frequency is generated by acrystal oscillator 132008 and is input into a fixed counter 132010 toscale the frequency to a suitable value. The outputs of the fixedcounter 132010 and the programmable counter 132006 are applied to aphase/frequency detector 132012. The output of the phase/frequencydetector 132012 is applied to an amplifier/active filter circuit 132014to generate a tuning voltage V_(t) that is applied to a voltagecontrolled oscillator 132016 (VCO). The VCO 132016 applies the outputfrequency f₀ to an ultrasonic transducer portion of the ultrasonicelectromechanical system 132002, shown here modeled as an equivalentelectrical circuit. The voltage and current signals applied to theultrasonic transducer are monitored by a voltage sensor 132018 and acurrent sensor 132020.

The outputs of the voltage and current sensors 132018, 13020 are appliedto another phase/frequency detector 132022 to determine the phase anglebetween the voltage and current as measured by the voltage and currentsensors 132018, 13020. The output of the phase/frequency detector 132022is applied to one channel of a high speed analog to digital converter132024 (ADC) and is provided to the processor 132004 therethrough.Optionally, the outputs of the voltage and current sensors 132018,132020 may be applied to respective channels of the two-channel ADC132024 and provided to the processor 132004 for zero crossing, FFT, orother algorithm described herein for determining the phase angle betweenthe voltage and current signals applied to the ultrasonicelectromechanical system 132002.

Optionally the tuning voltage V_(t), which is proportional to the outputfrequency f₀, may be fed back to the processor 132004 via the ADC132024. This provides the processor 132004 with a feedback signalproportional to the output frequency f₀ and can use this feedback toadjust and control the output frequency f₀.

Estimating the State of the Jaw (Pad Burn Through, Staples, BrokenBlade, Bone In Jaw, Tissue In Jaw)

A challenge with ultrasonic energy delivery is that ultrasonic acousticsapplied on the wrong materials or the wrong tissue can result in devicefailure, for example, clamp arm pad burn through or ultrasonic bladebreakage. It is also desirable to detect what is located in the jaws ofan end effector of an ultrasonic device and the state of the jawswithout adding additional sensors in the jaws. Locating sensors in thejaws of an ultrasonic end effector poses reliability, cost, andcomplexity challenges.

Ultrasonic spectroscopy smart blade algorithm techniques may be employedfor estimating the state of the jaw (clamp arm pad burn through,staples, broken blade, bone in jaw, tissue in jaw, back-cutting with jawclosed, etc.) based on the impedance

${Z_{g}(t)} = \frac{V_{g}(t)}{I_{g}(t)}$

of an ultrasonic transducer configured to drive an ultrasonic transducerblade, in accordance with at least one aspect of the present disclosure.The impedance Z_(g)(t), magnitude |Z|, and phase φ are plotted as afunction of frequency f.

Dynamic mechanical analysis (DMA), also known as dynamic mechanicalspectroscopy or simply mechanical spectroscopy, is a technique used tostudy and characterize materials. A sinusoidal stress is applied to amaterial, and the strain in the material is measured, allowing thedetermination of the complex modulus of the material. The spectroscopyas applied to ultrasonic devices includes exciting the tip of theultrasonic blade with a sweep of frequencies (compound signals ortraditional frequency sweeps) and measuring the resulting compleximpedance at each frequency. The complex impedance measurements of theultrasonic transducer across a range of frequencies are used in aclassifier or model to infer the characteristics of the ultrasonic endeffector. In one aspect, the present disclosure provides a technique fordetermining the state of an ultrasonic end effector (clamp arm, jaw) todrive automation in the ultrasonic device (such as disabling power toprotect the device, executing adaptive algorithms, retrievinginformation, identifying tissue, etc.).

FIG. 19 is a spectra 132030 of an ultrasonic device with a variety ofdifferent states and conditions of the end effector where the impedanceZ_(g)(t), magnitude |Z|, and phase φ are plotted as a function offrequency f, in accordance with at least one aspect of the presentdisclosure. The spectra 132030 is plotted in three-dimensional spacewhere frequency (Hz) is plotted along the x-axis, phase (Rad) is plottedalong the y-axis, and magnitude (Ohms) is plotted along the z-axis.

Spectral analysis of different jaw bites and device states producesdifferent complex impedance characteristic patterns (fingerprints)across a range of frequencies for different conditions and states. Eachstate or condition has a different characteristic pattern in 3D spacewhen plotted. These characteristic patterns can be used to estimate thecondition and state of the end effector. FIG. 19 shows the spectra forair 132032, clamp arm pad 132034, chamois 132036, staple 132038, andbroken blade 132040. The chamois 132036 may be used to characterizedifferent types of tissue.

The spectra 132030 can be evaluated by applying a low-power electricalsignal across the ultrasonic transducer to produce a non-therapeuticexcitation of the ultrasonic blade. The low-power electrical signal canbe applied in the form of a sweep or a compound Fourier series tomeasure the impedance

${Z_{g}(t)} = \frac{V_{g}(t)}{I_{g}(t)}$

across the ultrasonic transducer at a range of frequencies in series(sweep) or in parallel (compound signal) using an FFT.

Methods of Classification of New Data

For each characteristic pattern, a parametric line can be fit to thedata used for training using a polynomial, a Fourier series, or anyother form of parametric equation as may be dictated by convenience. Anew data point is then received and is classified by using the Euclideanperpendicular distance from the new data point to the trajectory thathas been fitted to the characteristic pattern training data. Theperpendicular distance of the new data point to each of the trajectories(each trajectory representing a different state or condition) is used toassign the point to a state or condition.

The probability distribution of distance of each point in the trainingdata to the fitted curve can be used to estimate the probability of acorrectly classified new data point. This essentially constructs atwo-dimensional probability distribution in a plane perpendicular to thefitted trajectory at each new data point of the fitted trajectory. Thenew data point can then be included in the training set based on itsprobability of correct classification to make an adaptive, learningclassifier that readily detects high-frequency changes in states butadapts to slow occurring deviations in system performance, such as adevice getting dirty or the pad wearing out.

FIG. 20 is a graphical representation of a plot 132042 of a set of 3Dtraining data set (S), where ultrasonic transducer impedance Z_(g)(t),magnitude |Z|, and phase φ are plotted as a function of frequency f, inaccordance with at least one aspect of the present disclosure. The 3Dtraining data set (S) plot 132042 is graphically depicted inthree-dimensional space where phase (Rad) is plotted along the x-axis,frequency (Hz) is plotted along the y-axis, magnitude (Ohms) is plottedalong the z-axis, and a parametric Fourier series is fit to the 3Dtraining data set (S). A methodology for classifying data is based onthe 3D training data set (S0 is used to generate the plot 132042).

The parametric Fourier series fit to the 3D training data set (S) isdefined by:

$\overset{\rightarrow}{p} = {{\overset{\rightarrow}{a}}_{0} + {\sum\limits_{n = 1}^{\infty}\left( {{{\overset{\rightarrow}{a}}_{n}\mspace{11mu} \cos \mspace{11mu} \frac{n\; \pi \; t}{L}} + {{\overset{\rightarrow}{b}}_{n}\mspace{11mu} \sin \mspace{11mu} \frac{n\; \pi \; t}{L}}} \right)}}$

For a new point {right arrow over (z)}, the perpendicular distance from{right arrow over (p)} to {right arrow over (z)} is found by:

$\begin{matrix}{D = {{\overset{\rightarrow}{p} - \overset{\rightarrow}{z}}}} & \; \\{{When}\text{:}} & \; \\{\frac{\partial D}{\partial T} = 0} & \; \\{{Then}\text{:}} & \; \\{D = D_{\bot}} & \;\end{matrix}$

A probability distribution of D can be used to estimate the probabilityof a data point {right arrow over (z)} belonging to the group S.

Control

Based on the classification of data measured before, during, or afteractivation of the ultrasonic transducer/ultrasonic blade, a variety ofautomated tasks and safety measures can be implemented. Similarly, thestate of the tissue located in the end effector and temperature of theultrasonic blade also can be inferred to some degree, and used to betterinform the user of the state of the ultrasonic device or protectcritical structures, etc. Temperature control of an ultrasonic blade isdescribed in commonly owned U.S. Provisional Patent Application No.62/640,417, filed Mar. 8, 2018, titled TEMPERATURE CONTROL IN ULTRASONICDEVICE AND CONTROL SYSTEM THEREFOR, which is incorporated herein byreference in its entirety.

Similarly, power delivery can be reduced when there is a highprobability that the ultrasonic blade is contacting the clamp arm pad(e.g., without tissue in between) or if there is a probability that theultrasonic blade has broken or that the ultrasonic blade is touchingmetal (e.g., a staple). Furthermore, back-cutting can be disallowed ifthe jaw is closed and no tissue is detected between the ultrasonic bladeand the clamp arm pad.

Integration of Other Data to Improve Classification

This system can be used in conjunction with other information providedby sensors, the user, metrics on the patient, environmental factors,etc., by combing the data from this process with the aforementioned datausing probability functions and a Kalman filter. The Kalman filterdetermines the maximum likelihood of a state or condition occurringgiven a plethora of uncertain measurements of varying confidence. Sincethis method allows for an assignment of probability to a newlyclassified data point, this algorithm's information can be implementedwith other measures or estimates in a Kalman filter.

FIG. 21 is a logic flow diagram 132044 depicting a control program or alogic configuration to determine jaw conditions based on the compleximpedance characteristic pattern (fingerprint), in accordance with atleast one aspect of the present disclosure. Prior to determining jawconditions based on the complex impedance characteristic pattern(fingerprint), a database is populated with reference complex impedancecharacteristic patterns or a training data sets (S) that characterizevarious jaw conditions, including, without limitation, air 132032, clamparm pad 132034, chamois 132036, staple 132038, broken blade 132040, asshown in FIG. 82, and a variety of tissue types and conditions. Thechamois dry or wet, full byte or tip, may be used to characterizedifferent types of tissue. The data points used to generate referencecomplex impedance characteristic patterns or a training data set (S) areobtained by applying a sub-therapeutic drive signal to the ultrasonictransducer, sweeping the driving frequency over a predetermined range offrequencies from below resonance to above resonance, measuring thecomplex impedance at each of the frequencies, and recording the datapoints. The data points are then fit to a curve using a variety ofnumerical methods including polynomial curve fit, Fourier series, and/orparametric equation. A parametric Fourier series fit to the referencecomplex impedance characteristic patterns or a training data set (S) isdescribed herein.

Once the reference complex impedance characteristic patterns or atraining data sets (S) are generated, the ultrasonic instrument measuresnew data points, classifies the new points, and determines whether thenew data points should be added to the reference complex impedancecharacteristic patterns or a training data sets (S).

Turning now to the logic flow diagram of FIG. 21, in one aspect, thecontrol circuit measures 132046 a complex impedance of an ultrasonictransducer, wherein the complex impedance is defined as

${Z_{g}(t)} = {\frac{V_{g}(t)}{I_{g}(t)}.}$

The control circuit receives 132048 a complex impedance measurement datapoint and compares 132050 the complex impedance measurement data pointto a data point in a reference complex impedance characteristic pattern.The control circuit classifies 132052 the complex impedance measurementdata point based on a result of the comparison analysis and assigns132054 a state or condition of the end effector based on the result ofthe comparison analysis.

In one aspect, the control circuit receives the reference compleximpedance characteristic pattern from a database or memory coupled tothe processor. In one aspect, the control circuit generates thereference complex impedance characteristic pattern as follows. A drivecircuit coupled to the control circuit applies a nontherapeutic drivesignal to the ultrasonic transducer starting at an initial frequency,ending at a final frequency, and at a plurality of frequenciestherebetween. The control circuit measures the impedance of theultrasonic transducer at each frequency and stores a data pointcorresponding to each impedance measurement. The control circuit curvefits a plurality of data points to generate a three-dimensional curve ofrepresentative of the reference complex impedance characteristicpattern, wherein the magnitude |Z| and phase φ are plotted as a functionof frequency f. The curve fitting includes a polynomial curve fit, aFourier series, and/or a parametric equation.

In one aspect, the control circuit receives a new impedance measurementdata point and classifies the new impedance measurement data point usinga Euclidean perpendicular distance from the new impedance measurementdata point to a trajectory that has been fitted to the reference compleximpedance characteristic pattern. The control circuit estimates aprobability that the new impedance measurement data point is correctlyclassified. The control circuit adds the new impedance measurement datapoint to the reference complex impedance characteristic pattern based onthe probability of the estimated correct classification of the newimpedance measurement data point. In one aspect, the control circuitclassifies data based on a training data set (S), where the trainingdata set (S) comprises a plurality of complex impedance measurementdata, and curve fits the training data set (S) using a parametricFourier series, wherein S is defined herein and wherein the probabilitydistribution is used to estimate the probability of the new impedancemeasurement data point belonging to the group S.

State of Jaw Classifier Based on Model

There has been an existing interest in classifying matter located withinthe jaws of an ultrasonic device including tissue types and condition.In various aspects, it can be shown that with high data sampling andsophisticated pattern recognition this classification is possible. Theapproach is based on impedance as a function of frequency, wheremagnitude, phase, and frequency are plotted in 3D the patterns look likeribbons as shown in FIGS. 19 and 20 and the logic flow diagram of FIG.21. This disclosure provides an alternative smart blade algorithmapproach that is based on a well-established model for piezoelectrictransducers.

By way of example, the equivalent electrical lumped parameter model isknown to be an accurate model of the physical piezoelectric transducer.It is based on the Mittag-Leffler expansion of a tangent near amechanical resonance. When the complex impedance or the complexadmittance is plotted as an imaginary component versus a real component,circles are formed. FIG. 22 is a circle plot 132056 of complex impedanceplotted as an imaginary component versus real components of apiezoelectric vibrator, in accordance with at least one aspect of thepresent disclosure. FIG. 23 is a circle plot 132058 of complexadmittance plotted as an imaginary component versus real components of apiezoelectric vibrator, in accordance with at least one aspect of thepresent disclosure. The circles depicted in FIGS. 22 and 23 are takenfrom the IEEE 177 Standard, which is incorporated herein by reference inits entirety. Tables 1-4 are taken from the IEEE 177 Standard anddisclosed herein for completeness.

The circle is created as the frequency is swept from below resonance toabove resonance. Rather than stretching the circle out in 3D, a circleis identified and the radius (r) and offsets (a, b) of the circle areestimated. These values are then compared with established values forgiven conditions. These conditions may be: 1) open nothing in jaws, 2)tip bite 3) full bite and staple in jaws. If the sweep generatesmultiple resonances, circles of different characteristics will bepresent for each resonance. Each circle will be drawn out before thenext if the resonances are separated. Rather than fitting a 3D curvewith a series approximation, the data is fitted with a circle. Theradius (r) and offsets (a, b) can be calculated using a processorprogrammed to execute a variety of mathematical or numerical techniquesdescribed below. These values may be estimated by capturing an image ofa circle and, using image processing techniques, the radius (r) andoffsets (a, b) that define the circle are estimated.

FIG. 24 is a circle plot 132060 of complex admittance for a 55.5 kHzultrasonic piezoelectric transducer for lumped parameters inputs andoutputs specified hereinbelow. Values for a lumped parameter model wereused to generate the complex admittance. A moderate load was applied inthe model. The obtained admittance circle generated in MathCad is shownin FIG. 24. The circle plot 132060 is formed when the frequency is sweptfrom 54 to 58 kHz.

The lumped parameter input values are:

Co=3.0 nF

Cs=8.22 pF

Ls=1.0 H

Rs=450Ω

The outputs of the model based on the inputs are:

$\begin{matrix}{{am} = {\frac{{D \cdot C} - {B \cdot C}}{{A \cdot C} - B^{2}} = {1.013 \cdot 10^{3}}}} \\{{bm} = {\frac{{A \cdot E} - {B \cdot D}}{{A \cdot C} - B^{2}} = {- 954.585}}} \\{{rm} = {{\frac{1}{fpts}\left( {\sum\limits_{i}^{fpts}\sqrt[2]{\left( {\left( {{Zout}_{1,i} = {am}} \right)^{2} + \left( {{Zout}_{2,i} - {bm}} \right)^{2}} \right)}} \right)} = {1.012 \cdot 10^{3}}}}\end{matrix}$

The output values are used to plot the circle plot 132060 shown in FIG.24. The circle plot 132060 has a radius (r) and the center 132062 isoffset (a, b) from the origin 132064 as follows:

r=1.012*10³

a=1.013*10³

b=−954.585

The summations A-E specified below are needed to estimate the circleplot 132060 plot for the example given in FIG. 24, in accordance with atleast one aspect of the present disclosure. Several algorithms exist tocalculate a fit to a circle. A circle is defined by its radius (r) andoffsets (a, b) of the center from the origin:

r ²=(x−a)²+(y−b)²

The modified least squares method (Umbach and Jones) is convenient inthat there a simple close formed solution for a, b, and r.

$\hat{a} = \frac{{DC} - {BE}}{{AC} - B^{2}}$$\hat{b} = \frac{{AE} - {BD}}{{AC} - B^{2}}$$\hat{r} = {\frac{1}{n}{\sum\limits_{i = 1}^{n}\sqrt{\left( {x_{i} - \hat{a}} \right)^{2} + \left( {y_{i} - \hat{b}} \right)^{2}}}}$

The caret symbol over the variable “a” indicates an estimate of the truevalue. A, B, C, D, and E are summations of various products which arecalculated from the data. They are included herein for completeness asfollows:

$\mspace{20mu} {A:={{{{fpts} \cdot {\sum\limits_{i}^{fpts}\left( {Zout}_{1,i} \right)^{2}}} - \left( {\sum\limits_{i}^{fpts}\left( {Zout}_{1,i} \right)} \right)^{2}} = {5.463 \cdot 10^{10}}}}$$B:= {{{{fpts}{\sum\limits_{i}^{fpts}\left( {{Zout}_{1,i} \cdot {Zout}_{2,i}} \right)}} - \left( {\left( {\sum\limits_{i}^{fpts}\left( {Zout}_{1,i} \right)} \right) \cdot \left( {\sum\limits_{i}^{fpts}\left( {Zout}_{2,i} \right)} \right)} \right)} = {5.461 \cdot 10^{7}}}$$\mspace{20mu} {C:={{{{fpts}{\sum\limits_{i}^{fpts}\left( {Zout}_{2,i} \right)^{2}}} - \left( {\sum\limits_{i}^{fpts}\left( {Zout}_{2,i} \right)} \right)^{2}} = {5.445 \cdot 10^{10}}}}$$D:= {{0.5 \cdot \left( {{{fpts}{\sum\limits_{i}^{fpts}\left( {{Zout}_{1,i} \cdot \left( {Zout}_{2,i} \right)^{2}} \right)}} - {\left( {\sum\limits_{i}^{fpts}\left( {Zout}_{1,i} \right)} \right) \cdot \left( {\sum\limits_{i}^{fpts}\left( {Zout}_{2,i} \right)^{2}} \right)} + {{fpts}{\sum\limits_{i}^{fpts}\left( {Zout}_{1,i}^{3} \right)}} - {\left( {\sum\limits_{i}^{fpts}\left( {Zout}_{1,i} \right)} \right) \cdot \left( {\sum\limits_{i}^{fpts}\left( {Zout}_{1,i} \right)^{2}} \right)}} \right)} = {5.529 \cdot 10^{3}}}$$E:={{0.5 \cdot \left( {{{fpts}{\sum\limits_{i}^{fpts}\left( {{Zout}_{2,i} \cdot \left( {Zout}_{1,i} \right)^{2}} \right)}} - {\left( {\sum\limits_{i}^{fpts}\left( {Zout}_{2,i} \right)} \right) \cdot \left( {\sum\limits_{i}^{fpts}\left( {Zout}_{1,i} \right)^{2}} \right)} + {{fpts}{\sum\limits_{i}^{fpts}\left( {Zout}_{2,i}^{3} \right)}} - {\left( {\sum\limits_{i}^{fpts}\left( {Zout}_{2,i} \right)} \right) \cdot \left( {\sum\limits_{i}^{fpts}\left( {Zout}_{2,i} \right)^{2}} \right)}} \right)} = {{- 5.192} \cdot 10^{13}}}$

Z1,i is a first vector of the real components referred to asconductance;

Z2,i is a second of the imaginary components referred to as susceptance;and

Z3,i is a third vector that represents the frequencies at whichadmittances are calculated.

This disclosure will work for ultrasonic systems and may possibly beapplied to electrosurgical systems, even though electrosurgical systemsdo not rely on a resonance.

FIGS. 25-29 illustrate images taken from an impedance analyzer showingimpedance/admittance circle plots for an ultrasonic device with the endeffector jaw in various open or closed configurations and loading. Thecircle plots in solid line depict impedance and the circle plots inbroken lines depict admittance, in accordance with at least one aspectof the present disclosure. By way of example, the impedance/admittancecircle plots are generated by connecting an ultrasonic device to animpedance analyzer. The display of the impedance analyzer is set tocomplex impedance and complex admittance, which can be selectable fromthe front panel of the impedance analyzer. An initial display may beobtained with the jaw of the ultrasonic end effector in an open positionand the ultrasonic device in an unloaded state, as described below inconnection with FIG. 25, for example. The autoscale display function ofthe impedance analyzer may be used to generate both the compleximpedance and admittance circle plots. The same display is used forsubsequent runs of the ultrasonic device with different loadingconditions as shown in the subsequent FIGS. 25-29. A LabVIEW applicationmay be employed to upload the data files. In another technique, thedisplay images may be captured with a camera, such as a smartphonecamera, like an iPhone or Android. As such, the image of the display mayinclude some “keystone-ing” and in general may not appear to be parallelto the screen. Using this technique, the circle plot traces on thedisplay will appear distorted in the captured image. With this approach,the material located in the jaws of the ultrasonic end effector can beclassified.

The complex impedance and complex admittance are just the reciprocal ofone another. No new information should be added by looking at both.Another consideration includes determining how sensitive the estimatesare to noise when using complex impedance or complex admittance.

In the examples illustrated in FIGS. 25-29, the impedance analyzer isset up with a range to just capture the main resonance. By scanning overa wider range of frequencies more resonances may be encountered andmultiple circle plots may be formed. An equivalent circuit of anultrasonic transducer may be modeled by a first “motional” branch havinga serially connected inductance Ls, resistance Rs and capacitance Csthat define the electromechanical properties of the resonator, and asecond capacitive branch having a static capacitance C0. In theimpedance/admittance plots shown in FIGS. 25-29 that follow, the valuesof the components of the equivalent circuit are:

Ls=L1=1.1068 H

Rs=R1=311.352Ω

Cs=C1=7.43265 pF

C0=C0=3.64026 nF

The oscillator voltage applied to the ultrasonic transducer is 500 mVand the frequency is swept from 55 kHz to 56 kHz. The impedance (Z)scale is 200 Ω/div and the admittance (Y) scale is 500 μS/div.Measurements of values that may characterize the impedance (Z) andadmittance (Y) circle plots may be obtained at the locations on thecircle plots as indicated by an impedance cursor and an admittancecursor.

State of Jaw: Open With No Loading

FIG. 25 is a graphical display 132066 of an impedance analyzer showingcomplex impedance (Z)/admittance (Y) circle plots 132068, 132070 for anultrasonic device with the jaw open and no loading where a circle plot132068 in solid line depicts complex impedance and a circle plot 132070in broken line depicts complex admittance, in accordance with at leastone aspect of the present disclosure. The oscillator voltage applied tothe ultrasonic transducer is 500 mV and the frequency is swept from 55kHz to 56 kHz. The impedance (Z) scale is 200 Ω/div and the admittance(Y) scale is 500 μS/div. Measurements of values that may characterizethe complex impedance (Z) and admittance (Y) circle plots 132068, 132070may be obtained at locations on the circle plots 132068, 132070 asindicated by the impedance cursor 132072 and the admittance cursor132074. Thus, the impedance cursor 132072 is located at a portion of theimpedance circle plot 132068 that is equivalent to about 55.55 kHz, andthe admittance cursor 132074 is located at a portion of the admittancecircle plot 132070 that is equivalent to about 55.29 kHz. As depicted inFIG. 25, the position of the impedance cursor 132072 corresponds tovalues of:

R=1.66026Ω

X=−697.309Ω

Where R is the resistance (real value) and X is the reactance (imaginaryvalue). Similarly, the position of the admittance cursor 132074corresponds to values of:

G=64.0322 μS

B=1.63007 mS

Where G is the conductance (real value) and B is susceptance (imaginaryvalue).

State Of Jaw: Clamped On Dry Chamois

FIG. 26 is a graphical display 132076 of an impedance analyzer showingcomplex impedance (Z)/admittance (Y) circle plots 132078, 132080 for anultrasonic device with the jaw of the end effector clamped on drychamois where the impedance circle plot 132078 is shown in solid lineand the admittance circle plot 132080 is shown in broken line, inaccordance with at least one aspect of the present disclosure. Thevoltage applied to the ultrasonic transducer is 500 mV and the frequencyis swept from 55 kHz to 56 kHz. The impedance (Z) scale is 200 Ω/div andthe admittance (Y) scale is 500 μS/div.

Measurements of values that may characterize the complex impedance (Z)and admittance (Y) circle pots 132078, 132080 may be obtained atlocations on the circle plots 132078, 132080 as indicated by theimpedance cursor 132082 and the admittance cursor 132084. Thus, theimpedance cursor 132082 is located at a portion of the impedance circleplot 132078 that is equivalent to about 55.68 kHz, and the admittancecursor 132084 is located at a portion of the admittance circle plot132080 that is equivalent to about 55.29 kHz. As depicted in FIG. 26,the position of the impedance cursor 132082 corresponds to values of:

R=434.577Ω

X=−758.772Ω

Where R is the resistance (real value) and X is the reactance (imaginaryvalue).

Similarly, the position of the admittance cursor 132084 corresponds tovalues of:

G=85.1712 μS

B=1.49569 mS

Where G is the conductance (real value) and B is susceptance (imaginaryvalue).

State Of Jaw: Tip Clamped On Moist Chamois

FIG. 27 is a graphical display 132086 of an impedance analyzer showingcomplex impedance (Z)/admittance (Y) circle plots 132098, 132090 for anultrasonic device with the jaw tip clamped on moist chamois where theimpedance circle plot 132088 is shown in solid line and the admittancecircle plot 132090 is shown in broken line, in accordance with at leastone aspect of the present disclosure. The voltage applied to theultrasonic transducer is 500 mV and the frequency is swept from 55 kHzto 56 kHz. The impedance (Z) scale is 200 Ω/div and the admittance (Y)scale is 500 μS/div.

Measurements of values that may characterize the complex impedance (Z)and complex admittance (Y) circle plots 132088, 132090 may be obtainedat locations on the circle plots 132088, 132090 as indicated by theimpedance cursor 132092 and the admittance cursor 132094. Thus, theimpedance cursor 132092 is located at a portion of the impedance circleplot 132088 that is equivalent to about 55.68 kHz, and the admittancecursor 132094 is located at a portion of the admittance circle plot132090 that is equivalent to about 55.29 kHz. As depicted in FIG. 28,the impedance cursor 132092 corresponds to values of:

R=445.259Ω

X=−750.082Ω

Where R is the resistance (real value) and X is the reactance (imaginaryvalue). Similarly, the admittance cursor 132094 corresponds to valuesof:

G=96.2179 μS

B=1.50236 mS

Where G is the conductance (real value) and B is susceptance (imaginaryvalue).

State of Jaw: Fully Clamped on Moist Chamois

FIG. 28 is a graphical display 132096 of an impedance analyzer showingcomplex impedance (Z)/admittance (Y) circle plots 132098, 132100 for anultrasonic device with the jaw fully clamped on moist chamois where theimpedance circle plot 132098 is shown in solid line and the admittancecircle plot 132100 is shown in broken line, in accordance with at leastone aspect of the present disclosure. The voltage applied to theultrasonic transducer is 500 mV and the frequency is swept from 55 kHzto 56 kHz. The impedance (Z) scale is 200 Ω/div and the admittance (Y)scale is 500 μS/div.

Measurements of values that may characterize the impedance andadmittance circle plots 132098, 132100 may be obtained at locations onthe circle plots 132098, 1332100 as indicated by the impedance cursor13212 and admittance cursor 132104. Thus, the impedance cursor 132102 islocated at a portion of the impedance circle plot 132098 equivalent toabout 55.63 kHz, and the admittance cursor 132104 is located at aportion of the admittance circle plot 132100 equivalent to about 55.29kHz. As depicted in FIG. 28, the impedance cursor 132102 corresponds tovalues of R, the resistance (real value, not shown), and X, thereactance (imaginary value, also not shown).

Similarly, the admittance cursor 132104 corresponds to values of:

G=137.272 μS

B=1.48481 mS

Where G is the conductance (real value) and B is susceptance (imaginaryvalue).

State of Jaw: Open With No Loading

FIG. 29 is a graphical display 132106 of an impedance analyzer showingimpedance (Z)/admittance (Y) circle plots where frequency is swept from48 kHz to 62 kHz to capture multiple resonances of an ultrasonic devicewith the jaw open and no loading where the area designated by therectangle 132108 shown in broken line is to help see the impedancecircle plots 132110 a, 132110 b, 132110 c shown in solid line and theadmittance circle plots 132112 a, 132112 b, 132112 c, in accordance withat least one aspect of the present disclosure. The voltage applied tothe ultrasonic transducer is 500 mV and the frequency is swept from 48kHz to 62 kHz. The impedance (Z) scale is 500 Ω/div and the admittance(Y) scale is 500 μS/div.

Measurements of values that may characterize the impedance andadmittance circle plots 132110 a-c, 132112 a-c may be obtained atlocations on the impedance and admittance circle plots 132110 a-c,132112 a-c as indicated by the impedance cursor 132114 and theadmittance cursor 132116. Thus, the impedance cursor 132114 is locatedat a portion of the impedance circle plots 132110 a-c equivalent toabout 55.52 kHz, and the admittance cursor 132116 is located at aportion of the admittance circle plot 132112 a-c equivalent to about59.55 kHz. As depicted in FIG. 29, the impedance cursor 132114corresponds to values of:

R=1.86163 kΩ

X=−536.229Ω

Where R is the resistance (real value) and X is the reactance (imaginaryvalue). Similarly, the admittance cursor 132116 corresponds to valuesof:

G=649.956 μS

B=2.51975 mS

Where G is the conductance (real value) and B is susceptance (imaginaryvalue).

Because there are only 400 samples across the sweep range of theimpedance analyzer, there are only a few points about a resonance. So,the circle on the right side becomes choppy. But this is only due to theimpedance analyzer and the settings used to cover multiple resonances.

When multiple resonances are present, there is more information toimprove the classifier. The circle plots 132110 a-c, 132112 a-c fit canbe calculated for each as encountered to keep the algorithm runningfast. So once there is a cross of the complex admittance, which impliesa circle, during the sweep, a fit can be calculated.

Benefits include in-the-jaw classifier based on data and a well-knownmodel for ultrasonic systems. Count and characterizations of circles arewell known in vision systems. So data processing is readily available.For example, a closed form solution exists to calculate the radius andaxes' offsets for a circle. This technique can be relatively fast.

TABLE 2 is a list of symbols used for lumped parameter model of apiezoelectric transducer (from IEEE 177 Standard).

TABLE 2 References Symbols Meaning SI Units Equations Tables FiguresB_(p) Equivalent parallel mho 2 susceptance of vibrator C_(o) Shunt(parallel) capacitance farad 2, 3, 4, 8 5 1, 4 in the equivalentelectric circuit C₁ Motional capacitance in the farad 2, 3, 4, 6, 5 1, 4equivalent electric circuit 8, 9 f Frequency hertz 3 f_(a) Antiresonancefrequency, hertz 2, 4 2, 3 zero susceptance f_(m) Frequency of maximumhertz 2, 4 2, 3 admittance (minimum impedance) f_(n) Frequency ofminimum hertz 2, 4 2, 3 admittance (maximum impedance) f_(p) Parallelresonance frequency hertz 2, 3 2, 4 2$({lossless}) = \frac{1}{2\; \pi \sqrt{L_{1}\frac{C_{1}C_{O}}{C_{1} + C_{O}}}}$f_(r) Resonance frequency, zero hertz 2, 4 2, 3 substance f_(B) Motional(series) resonance hertz 2, 3, 6, 7, 2, 4 2, 3, 6, 8 frequency 1/2 9,11a, 11b, 11c, 12, G_(p) Equivalent parallel 1 conductance of vibratorL₁ Motional inductance in the henry 8, 9 1, 4, 5 equivalent electriccircuit M $\begin{matrix}{{{Figure}\mspace{14mu} {of}\mspace{14mu} {merit}\mspace{14mu} {of}\mspace{14mu} a\mspace{14mu} {vibrator}} = \frac{Q}{r}} \\{M = \frac{1}{\omega_{s}C_{O}R_{1}}}\end{matrix}\quad$ dimensionless 10, 11a, 11b 3, 4, 5 Q$\quad\begin{matrix}{{{Quality}\mspace{14mu} {factor}\mspace{14mu} Q} = {\frac{\omega_{s}L_{1}}{R_{1}} =}} \\{\frac{1}{\omega_{s}C_{1}R_{1}} = {rM}}\end{matrix}$ dimensionless 12 3 6, 8 r${{Capacitance}\mspace{14mu} {ratio}\mspace{14mu} r} = \frac{C_{o}}{C_{1}}$dimensionless 2, 3, 10, 11 2, 3, 4, 5 8 R_(a) Impedance at zero phaseohm 2, 3 angle near antiresonance R_(e) Equivalent series resistance ohm1, 2 of vibrator R_(r) Impedance at f_(r) zero phase ohm 2, 3 angle R₁Motional resistance in the ohm 4, 8, 10, 2,5 1, 3, 4, equivalentelectric circuit 11a, 11b, 6, 7, 8 11c, 12 X_(e) Equivalent seriesreactance of ohm 1,2 vibrator X_(o) Reactance of shunt (parallel) ohm 1,4, 5 5 3, 7 capacitance at series${resonance} = \frac{1}{\omega_{s}C_{o}}$ X₁ Reactance of motional ohm2 2 (series) arm of vibratorX₁ =${{}_{}^{}{}_{}^{}} - \frac{1}{{}_{}^{}{}_{}^{}}$ Y Admittance ofvibrator mho 1 $Y = {{G_{p} + {{}_{}^{}{}_{}^{}}} = \frac{1}{z}}$ Y_(m)Maximum admittance of mho 3 vibrator Y_(n) Minimum admittance of mho 3vibrator Z Impedance of vibrator ohm 1 Z = Re +_(j)X_(e) Z_(m) Minimumimpedance of ohm 3 vibrator Z_(n) Maximum impedance of ohm 3 vibratorAbsolute value of impedance ohm 2 2${{of}\mspace{14mu} {vibrator}\mspace{14mu} Z} = \sqrt{R_{e}^{2} + X_{e}^{2}}$Absolute value of impedance ohm 2 at f_(m) (minimum impedance) Absolutevalue of impedance ohm 2 at f_(n) (maximum impedance) δ Normalizeddamping dimensionless 1 2 factorδ = _(ω)C_(o)R₁ Ω Normalized frequencydimensionless 1 2${{factor}\mspace{11mu} \Omega} = \frac{f^{2} - f_{s}^{2}}{f_{p}^{2} - f_{s}^{2}}$ω Circular (angular) frequency hertz 2 ω = 2πf ω_(s) Circular frequencyat motional hertz resonance ω_(s) = 2πfTABLE 3 is a list of symbols for the transmission network (from IEEE 177Standard).

TABLE 3 References Symbols Meaning SI Units Equations Tables Figures bNormalized compensation${{factor}\; 1} - \frac{1}{4\; \pi^{2}f_{s}^{2}C_{O}L_{O}}$dimensionless 4, 10 5 B Normalized admittance factor dimensionless 10 5C Normalized admittance factor dimensionless 10 5 C_(A-B) Straycapacitance between the terminals A-B (FIG. 4) farad C_(L) Loadcapacitance farad 6 4 C_(T) Shunt capacitance terminating transmissionfarad 4, 10 5 4 circuit C_(L1) Load capacitance farad 7 C_(L2) Loadcapacitance farad 7 e₂ Output voltage of volt 4 transmission networkf_(mT) Frequency of maximum hertz 10 transmission F_(sL1) Motionalresonance frequency hertz 7 of combination of vibrator and C_(L1)F_(sL2) Motional resonance frequency hertz 7 of combination of vibratorand C_(L2) i₁ Input current to transmission ampere 4 network L₀Compensation inductance henry 4 shunting vibrator M_(T) Figure of meritof dimensionless 4, 10 5 transmission network${termination} = {\frac{1}{2_{\pi}f_{s}C_{T}R_{T}} = \frac{X_{T}}{R_{T}}}$R_(T) Shunt resistance termination ohm 4, 11a, 5 4, 6, 7, 8 oftransmission network 11b, 11c, 12 R_(sL2) Standard resistor ohm 4, 5 5 7S Detector sensitivity smallest dimensionless 12 6 detectable currentchange/ current x Normalized frequency dimensionless 12${{factor}\; x} = {{\frac{f^{2}}{f_{s}^{2}} - 1} = \frac{\Omega}{r}}$X_(A-B) Reactance of stray ohm capacitance C_(A-B) X_(T) Reactance ofC_(T) at the ohm 4 5 motional resonance${{frequency}\; X_{T}} = \frac{1}{2_{\pi}f_{s}C_{T}}$ X_(mT)Normalized frequency factor dimensionless 5 at the frequency of maximumtransmission ΔC_(L) ΔC_(L) = C_(L2) − C_(L1) farad 6, 7 Δf Δf₁ = f_(sL1)− f_(sL2) hertz 6, 7 6, 8 Δf₁ Δf₁ = f_(sL1) − f_(s) hertz 6, 7 Δf₂ Δf₁ =f_(sL2) ⁻ _(fs) hertz 6, 7 *Refers to real roots; complex roots to bedisregarded.

TABLE 4 is a list of solutions for various characteristic frequencies(from IEEE 177 Standard).

Solutions for the Various Characteristic Frequencies

TABLE 4 Constituent Characteristic Equation for 57 IEEE FrequenciesMeaning Condition Frequency Root 14.S1¹ f_(m) Frequency of maximum =O−2δ²(Ω + r) − lower* f_(m) admittance (minimum 2Ωr(1 − Ω) − impedance)Ω² = O f_(a) Motional (series) X₁ = O Ω = O f_(a) resonance frequencyf_(r) Resonance frequency X_(e) = Ω (1 − Ω) − lower f_(r) B_(p) = O δ² =O f_(a) Antiresonance frequency X_(e) = Ω (1 − Ω) − upper f_(a) B_(p) =O δ² = O f_(p) Parallel resonance | =∞ | Ω = 1 f_(p) frequency(lossless) R₁ = O f_(n) Frequency of minimum =O −2δ²(Ω + r) − upper*f_(n) admittance (maximum 2Ωr(1 − Ω) − impedance) Ω² = O *Refers to realroots; complex roots to be disregarded

TABLE 5 is a list of losses of three classes of piezoelectric materials.

TABLE 5 Minimum Values for the Ratio Q^(r)/r to be Expected for VariousTypes of Piezoelectric Vibrators Type of Piezoelectric Vibrator Q = Mr rQ^(r)/r min Piezoelectric Ceramics 90-500  2-40  200 Water-Soluble200-50,000 3-500 80 Piezoelectric Crystals Quartz 10⁴-10⁷    100-50,0002000

TABLE 6 illustrates jaw conditions, estimated parameters of a circlebased on real time measurements of complex impedance/admittance, radius(re) and offsets (ae and be) of the circle represented by measuredvariables Re, Ge, Xe, Be, and parameters of a reference circle plots, asdescribed in FIGS. 25-29, based on real time measurements of compleximpedance/admittance, radius (rr) and offsets (ar, br) of the referencecircle represented by reference variables Rref, Gref, Xref, Bref. Thesevalues are then compared with established values for given conditions.These conditions may be: 1) open with nothing in jaws, 2) tip bite 3)full bite and staple in jaws. The equivalent circuit of the ultrasonictransducer was modeled as follows and the frequency was swept from 55kHz to 56 kHz:

Ls=L1=1.1068 H

Rs=R1=311.352Ω

Cs=C1=7.43265 pF and

C0=C0=3.64026 nF

TABLE 6 Reference Jaw Reference Circle Plot Conditions R_(ref) (Ω)G_(ref) (μS) X_(ref) (Ω) B_(ref) (mS) Jaw open and 1.66026 64.0322−697.309 1.63007 no loading Jaw clamped on 434.577 85.1712 −758.7721.49569 dry chamois Jaw tip clamped 445.259 96.2179 −750.082 1.50236 onmoist chamois Jaw fully clamped 137.272 1.48481 on moist chamois

In use, the ultrasonic generator sweeps the frequency, records themeasured variables, and determines estimates Re, Ge, Xe, Be. Theseestimates are then compared to reference variables Rref, Gref, Xref,Bref stored in memory (e.g., stored in a look-up table) and determinesthe jaw conditions. The reference jaw conditions shown in TABLE 6 areexamples only. Additional or fewer reference jaw conditions may beclassified and stored in memory. These variables can be used to estimatethe radius and offsets of the impedance/admittance circle.

FIG. 30 is a logic flow diagram 132120 of a process depicting a controlprogram or a logic configuration to determine jaw conditions based onestimates of the radius (r) and offsets (a, b) of animpedance/admittance circle, in accordance with at least one aspect ofthe present disclosure. Initially a data base or lookup table ispopulated with reference values based on reference jaw conditions asdescribed in connection with FIGS. 25-29 and TABLE 6. A reference jawcondition is set and the frequency is swept from a value below resonanceto a value above resonance. The reference values Rref, Gref, Xref, Brefthat define the corresponding impedance/admittance circle plot arestored in a database or lookup table. During use, under control of acontrol program or logic configuration a control circuit of thegenerator or instrument causes the frequency to sweep 132122 from belowresonance to above resonance. The control circuit measures and records132124 (e.g., stores in memory) the variables Re, Ge, Xe, Be that definethe corresponding impedance/admittance circle plot and compares 132126them to the reference values Rref, Gref, Xref, Bref stored in thedatabase or lookup table. The control circuit determines 132128, e.g.,estimates, the end effector jaw conditions based on the results of thecomparison.

Live Time Tissue Classification Using Electrical Parameters SealingWithout Cutting, RF/Ultrasonic Combination Technology, TailoredAlgorithms

In one aspect, the present disclosure provides an algorithm forclassifying tissue into groups. A tissue type may be determined 132152using the techniques described in FIGS. 19-21 under the headingESTIMATING THE STATE OF THE JAW (PAD BURN THROUGH, STAPLES, BROKENBLADE, BONE IN JAW, TISSUE IN JAW and/or FIGS. 22-30 under the headingSTATE OF JAW CLASSIFIER BASED ON MODEL and/or techniques for estimatingthe temperature of the ultrasonic blade are described in related USProvisional Patent Application No. 62/640,417, titled TEMPERATURECONTROL IN ULTRASONIC DEVICE AND CONTROL SYSTEM THEREFOR, to Nott et al,which is incorporated herein by reference in its entirety. The abilityto classify tissue in live time will allow for tailoring algorithms to aspecific tissue group. The tailored algorithms can optimize seal timesand hemostasis across all tissue types. In one aspect, the presentdisclosure provides a sealing algorithm to provide hemostasis needed forlarge vessels and quickly seal smaller structures that do not needextended energy activation. The ability to classify these distincttissue types allows for optimized algorithms for each group in livetime.

In this aspect, during the first 0.75 seconds of the activation, 3 RFelectrical parameters are used in a plot to classify tissue intodistinct groups. These electrical parameters are: Initial RF impedance(taken at 0.15 seconds), Minimum RF impedance in first 0.75 seconds, andthe amount of time the RF impedance slope is ˜0 in milliseconds. Aplurality of other times that these data points are taken could beimplemented. All of these data are collected in a set amount of time,and then using a Support Vector Machine (SVM) or another classificationalgorithm, the tissue can be classified into a distinct group in livetime. Each tissue group would have an algorithm specific to it thatwould be implemented for the remainder of the activation. Types of SVM'sinclude linear, polynomial, and radial basis function (RBF).

FIG. 31 is a three-dimensional graphical representation 132450 of radiofrequency (RF) tissue impedance classification, in accordance with atleast one aspect of the present disclosure. The x-axis represents theminimum RF impedance (Zmin) of the tissue, the y-axis represents initialRF impedance (Zinit) of the tissue, and the z-axis represents the amountof time that the derivative of the RF impedance (Z) of the tissue isapproximately 0. FIG. 31 shows a grouping of large vessels 132452, e.g.,carotids—thick tissue, and small vessels 132454, e.g., thyros—thintissue, when using the three RF parameters of Initial RF impedance,Minimum RF Impedance, and the amount of time the derivative (slope) ofthe RF impedance is approximately zero within the first 0.75 seconds ofactivation. A distinction of this classification method is that thetissue type can be classified in a set amount of time. The advantage tothis method is a tissue specific algorithm can be chosen towards thebeginning of the activation, so specialized tissue treatment can beginbefore the exit out of the RF bathtub. It will be appreciated that inthe context of tissue impedance under the influence of RF energy abathtub region is a curve wherein the tissue impedance drops after theinitial application of RF energy and stabilizes until the tissue beginsto dry out. Thereafter the tissue impedance increases. Thus, theimpedance versus time curve resembles the shape of a “bathtub.”

This data were used to train and test a Support Vector Machine to groupthick and thin tissue, and accurately classified 94% of the time.

In one aspect, the present disclosure provides a device comprising onecombo RF/Ultrasonic algorithm that is used for all tissue types and ithas been identified that seal speeds for thin tissues are longer thannecessary, however larger vessels and thicker structures could benefitfrom an extended activation. This classification scheme will enable thecombo RF/ultrasonic device to seal small structures with optimal speedsand burst pressures, and to seal larger structures to ensure maximumhemostasis is achieved.

FIG. 32 is a three-dimensional graphical representation 132460 of radiofrequency (RF) tissue impedance analysis, in accordance with at leastone aspect of the present disclosure. The x=axis represents the minimumRF impedance (Zmin) of the tissue, the y-axis represents the initial RFimpedance (Zinit) of the tissue, and the z-axis represents the amount oftime that the derivative of the RF impedance (Z) of the tissue isapproximately 0. To determine if this classification model of thicktissue 132462 versus thin tissue 132464 was robust to different tissuetypes, data were added for various benchtop tissue types, and thetissues grouped into two distinct groups. It is possible to separatethese data into a plurality of groups if it is deemed beneficial ornecessary. The different thick tissue 132462 types include, for example,carotid, jejunum, mesentery, jugular, and liver tissue. The differentthin tissue 132464 types include, for example, thyro and thyro vein.

While several forms have been illustrated and described, it is not theintention of the applicant to restrict or limit the scope of theappended claims to such detail. Numerous modifications, variations,changes, substitutions, combinations, and equivalents to those forms maybe implemented and will occur to those skilled in the art withoutdeparting from the scope of the present disclosure. Moreover, thestructure of each element associated with the described forms can bealternatively described as a means for providing the function performedby the element. Also, where materials are disclosed for certaincomponents, other materials may be used. It is therefore to beunderstood that the foregoing description and the appended claims areintended to cover all such modifications, combinations, and variationsas falling within the scope of the disclosed forms. The appended claimsare intended to cover all such modifications, variations, changes,substitutions, modifications, and equivalents.

The foregoing detailed description has set forth various forms of thedevices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, and/or examples can beimplemented, individually and/or collectively, by a wide range ofhardware, software, firmware, or virtually any combination thereof.Those skilled in the art will recognize that some aspects of the formsdisclosed herein, in whole or in part, can be equivalently implementedin integrated circuits, as one or more computer programs running on oneor more computers (e.g., as one or more programs running on one or morecomputer systems), as one or more programs running on one or moreprocessors (e.g., as one or more programs running on one or moremicroprocessors), as firmware, or as virtually any combination thereof,and that designing the circuitry and/or writing the code for thesoftware and or firmware would be well within the skill of one of skillin the art in light of this disclosure. In addition, those skilled inthe art will appreciate that the mechanisms of the subject matterdescribed herein are capable of being distributed as one or more programproducts in a variety of forms, and that an illustrative form of thesubject matter described herein applies regardless of the particulartype of signal bearing medium used to actually carry out thedistribution.

Instructions used to program logic to perform various disclosed aspectscan be stored within a memory in the system, such as dynamic randomaccess memory (DRAM), cache, flash memory, or other storage.Furthermore, the instructions can be distributed via a network or by wayof other computer readable media. Thus a machine-readable medium mayinclude any mechanism for storing or transmitting information in a formreadable by a machine (e.g., a computer), but is not limited to, floppydiskettes, optical disks, compact disc, read-only memory (CD-ROMs), andmagneto-optical disks, read-only memory (ROMs), random access memory(RAM), erasable programmable read-only memory (EPROM), electricallyerasable programmable read-only memory (EEPROM), magnetic or opticalcards, flash memory, or a tangible, machine-readable storage used in thetransmission of information over the Internet via electrical, optical,acoustical or other forms of propagated signals (e.g., carrier waves,infrared signals, digital signals, etc.). Accordingly, thenon-transitory computer-readable medium includes any type of tangiblemachine-readable medium suitable for storing or transmitting electronicinstructions or information in a form readable by a machine (e.g., acomputer).

As used in any aspect herein, the term “control circuit” may refer to,for example, hardwired circuitry, programmable circuitry (e.g., acomputer processor comprising one or more individual instructionprocessing cores, processing unit, processor, microcontroller,microcontroller unit, controller, digital signal processor (DSP),programmable logic device (PLD), programmable logic array (PLA), orfield programmable gate array (FPGA)), state machine circuitry, firmwarethat stores instructions executed by programmable circuitry, and anycombination thereof. The control circuit may, collectively orindividually, be embodied as circuitry that forms part of a largersystem, for example, an integrated circuit (IC), an application-specificintegrated circuit (ASIC), a system on-chip (SoC), desktop computers,laptop computers, tablet computers, servers, smart phones, etc.Accordingly, as used herein “control circuit” includes, but is notlimited to, electrical circuitry having at least one discrete electricalcircuit, electrical circuitry having at least one integrated circuit,electrical circuitry having at least one application specific integratedcircuit, electrical circuitry forming a general purpose computing deviceconfigured by a computer program (e.g., a general purpose computerconfigured by a computer program which at least partially carries outprocesses and/or devices described herein, or a microprocessorconfigured by a computer program which at least partially carries outprocesses and/or devices described herein), electrical circuitry forminga memory device (e.g., forms of random access memory), and/or electricalcircuitry forming a communications device (e.g., a modem, communicationsswitch, or optical-electrical equipment). Those having skill in the artwill recognize that the subject matter described herein may beimplemented in an analog or digital fashion or some combination thereof.

As used in any aspect herein, the term “logic” may refer to an app,software, firmware and/or circuitry configured to perform any of theaforementioned operations. Software may be embodied as a softwarepackage, code, instructions, instruction sets and/or data recorded onnon-transitory computer readable storage medium. Firmware may beembodied as code, instructions or instruction sets and/or data that arehard-coded (e.g., nonvolatile) in memory devices.

As used in any aspect herein, the terms “component,” “system,” “module”and the like can refer to a computer-related entity, either hardware, acombination of hardware and software, software, or software inexecution.

As used in any aspect herein, an “algorithm” refers to a self-consistentsequence of steps leading to a desired result, where a “step” refers toa manipulation of physical quantities and/or logic states which may,though need not necessarily, take the form of electrical or magneticsignals capable of being stored, transferred, combined, compared, andotherwise manipulated. It is common usage to refer to these signals asbits, values, elements, symbols, characters, terms, numbers, or thelike. These and similar terms may be associated with the appropriatephysical quantities and are merely convenient labels applied to thesequantities and/or states.

A network may include a packet switched network. The communicationdevices may be capable of communicating with each other using a selectedpacket switched network communications protocol. One examplecommunications protocol may include an Ethernet communications protocolwhich may be capable permitting communication using a TransmissionControl Protocol/Internet Protocol (TCP/IP). The Ethernet protocol maycomply or be compatible with the Ethernet standard published by theInstitute of Electrical and Electronics Engineers (IEEE) titled “IEEE802.3 Standard”, published in December, 2008 and/or later versions ofthis standard. Alternatively or additionally, the communication devicesmay be capable of communicating with each other using an X.25communications protocol. The X.25 communications protocol may comply orbe compatible with a standard promulgated by the InternationalTelecommunication Union-Telecommunication Standardization Sector(ITU-T). Alternatively or additionally, the communication devices may becapable of communicating with each other using a frame relaycommunications protocol. The frame relay communications protocol maycomply or be compatible with a standard promulgated by ConsultativeCommittee for International Telegraph and Telephone (CCITT) and/or theAmerican National Standards Institute (ANSI). Alternatively oradditionally, the transceivers may be capable of communicating with eachother using an Asynchronous Transfer Mode (ATM) communications protocol.The ATM communications protocol may comply or be compatible with an ATMstandard published by the ATM Forum titled “ATM-MPLS NetworkInterworking 2.0” published August 2001, and/or later versions of thisstandard. Of course, different and/or after-developedconnection-oriented network communication protocols are equallycontemplated herein.

Unless specifically stated otherwise as apparent from the foregoingdisclosure, it is appreciated that, throughout the foregoing disclosure,discussions using terms such as “processing,” “computing,”“calculating,” “determining,” “displaying,” or the like, refer to theaction and processes of a computer system, or similar electroniccomputing device, that manipulates and transforms data represented asphysical (electronic) quantities within the computer system's registersand memories into other data similarly represented as physicalquantities within the computer system memories or registers or othersuch information storage, transmission or display devices.

One or more components may be referred to herein as “configured to,”“configurable to,” “operable/operative to,” “adapted/adaptable,” “ableto,” “conformable/conformed to,” etc. Those skilled in the art willrecognize that “configured to” can generally encompass active-statecomponents and/or inactive-state components and/or standby-statecomponents, unless context requires otherwise.

The terms “proximal” and “distal” are used herein with reference to aclinician manipulating the handle portion of the surgical instrument.The term “proximal” refers to the portion closest to the clinician andthe term “distal” refers to the portion located away from the clinician.It will be further appreciated that, for convenience and clarity,spatial terms such as “vertical”, “horizontal”, “up”, and “down” may beused herein with respect to the drawings. However, surgical instrumentsare used in many orientations and positions, and these terms are notintended to be limiting and/or absolute.

Those skilled in the art will recognize that, in general, terms usedherein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to claims containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations.

In addition, even if a specific number of an introduced claim recitationis explicitly recited, those skilled in the art will recognize that suchrecitation should typically be interpreted to mean at least the recitednumber (e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that typically a disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms unless context dictates otherwise. For example, the phrase “Aor B” will be typically understood to include the possibilities of “A”or “B” or “A and B.”

With respect to the appended claims, those skilled in the art willappreciate that recited operations therein may generally be performed inany order. Also, although various operational flow diagrams arepresented in a sequence(s), it should be understood that the variousoperations may be performed in other orders than those which areillustrated, or may be performed concurrently. Examples of suchalternate orderings may include overlapping, interleaved, interrupted,reordered, incremental, preparatory, supplemental, simultaneous,reverse, or other variant orderings, unless context dictates otherwise.Furthermore, terms like “responsive to,” “related to,” or otherpast-tense adjectives are generally not intended to exclude suchvariants, unless context dictates otherwise.

It is worthy to note that any reference to “one aspect,” “an aspect,”“an exemplification,” “one exemplification,” and the like means that aparticular feature, structure, or characteristic described in connectionwith the aspect is included in at least one aspect. Thus, appearances ofthe phrases “in one aspect,” “in an aspect,” “in an exemplification,”and “in one exemplification” in various places throughout thespecification are not necessarily all referring to the same aspect.Furthermore, the particular features, structures or characteristics maybe combined in any suitable manner in one or more aspects.

Any patent application, patent, non-patent publication, or otherdisclosure material referred to in this specification and/or listed inany Application Data Sheet is incorporated by reference herein, to theextent that the incorporated materials is not inconsistent herewith. Assuch, and to the extent necessary, the disclosure as explicitly setforth herein supersedes any conflicting material incorporated herein byreference. Any material, or portion thereof, that is said to beincorporated by reference herein, but which conflicts with existingdefinitions, statements, or other disclosure material set forth hereinwill only be incorporated to the extent that no conflict arises betweenthat incorporated material and the existing disclosure material.

In summary, numerous benefits have been described which result fromemploying the concepts described herein. The foregoing description ofthe one or more forms has been presented for purposes of illustrationand description. It is not intended to be exhaustive or limiting to theprecise form disclosed. Modifications or variations are possible inlight of the above teachings. The one or more forms were chosen anddescribed in order to illustrate principles and practical application tothereby enable one of ordinary skill in the art to utilize the variousforms and with various modifications as are suited to the particular usecontemplated. It is intended that the claims submitted herewith definethe overall scope.

Various aspects of the subject matter described herein are set out inthe following numbered examples:

Example 1. A method of classifying a tissue in live time, the methodcomprising:

activating, by a processor or control circuit, a radio frequency (RF)instrument for a first period of time T1, wherein the RF instrumentcontacts the tissue;

plotting, by the processor or control circuit, at least three electricalparameters associated with the tissue in contact with the RF instrumentto classify the tissue into distinct groups; and

applying, by the processor or control circuit, a classificationalgorithm to classify the tissue into a distinct group in live time.

Example 2. The method of Example 1, wherein plotting, by the processoror control circuit, at least three electrical parameters associated withthe tissue in contact with the RF instrument comprises plotting, by theprocessor or control circuit, an initial RF impedance of the tissue, aminimum RF impedance of the tissue, and an amount of time inmilliseconds that the RF impedance slope is ˜0.

Example 3. The method of any one or more of Examples 1 through 2,further comprising collecting, by the processor or control circuit, dataassociated with the at least three electrical parameters in apredetermined amount of time.

Example 4. The method of Example 3, wherein collecting, by the processoror control circuit, data associated with the at least three electricalparameters in a predetermined amount of time comprises collecting, bythe processor or control circuit, data associated with the at leastthree electrical parameters in within a first 0.75 seconds afteractivation of the radio frequency (RF) instrument.

Example 5. The method of any one or more of Examples 1 through 4,wherein applying, by the processor or control circuit, a classificationalgorithm to classify the tissue into a distinct group in live timecomprises applying, by the processor or control circuit, aclassification algorithm to classify the tissue into a distinct group inlive time using a support vector machine algorithm.

Example 6. The method of Example 5, wherein applying, by the processoror control circuit, a classification algorithm to classify the tissueinto a distinct group in live time using a support vector machinealgorithm comprises applying, by the processor or control circuit, aclassification algorithm to classify the tissue into a distinct group inlive time using a linear basis function, a polynomial basis function, ora radial basis function.

Example 7. The method of any one or more of Examples 1 through 6,further comprising applying, by the processor or control circuit, anactivation algorithm specific to each tissue group after the firstperiod T1.

Example 8. A surgical instrument comprising:

a radio frequency (RF) instrument comprising an end effector; and

a generator configured to supply power to the end effector, wherein thegenerator comprises a control circuit configured to:

-   -   activate the radio frequency (RF) instrument for a first period        of time T1, wherein the RF instrument contacts the tissue;    -   plot at least three electrical parameters associated with the        tissue in contact with the RF instrument to classify the tissue        into distinct groups; and    -   apply a classification algorithm to classify the tissue into a        distinct group in live time.

Example 9. The surgical instrument of Example 8, wherein the at leastthree electrical parameters associated with the tissue in contact withthe RF instrument comprise an initial RF impedance of the tissue, aminimum RF impedance of the tissue, and an amount of time inmilliseconds that the RF impedance slope is ˜0.

Example 10. The surgical instrument of any one or more of Examples 8through 9, wherein the control circuit is further configured to collectdata associated with the at least three electrical parameters in apredetermined amount of time.

Example 11. The surgical instrument of Example 10, wherein thepredetermined amount of time comprises a first 0.75 seconds afteractivation of the radio frequency (RF) instrument.

Example 12. The surgical instrument of any one or more of Examples 8through 11, wherein the control circuit is further configured toclassify the tissue into a distinct group in live time using a supportvector machine algorithm.

Example 13. The surgical instrument of Example 12, wherein the supportvector machine algorithm comprises a linear basis function, a polynomialbasis function, or a radial basis function.

Example 14. The surgical instrument of any one or more of Examples 8through 13, wherein the control circuit is further configured to applyan activation algorithm specific to each tissue group after the firstperiod T1.

Example 15. A generator for a surgical instrument, wherein the surgicalinstrument comprises a radio frequency (RF) instrument comprising an endeffector, the generator comprising:

a control circuit configured to:

-   -   activate the radio frequency (RF) instrument for a first period        of time T1, wherein the RF instrument contacts a tissue;    -   plot at least three electrical parameters associated with the        tissue in contact with the RF instrument to classify the tissue        into distinct groups; and    -   apply a classification algorithm to classify the tissue into a        distinct group in live time.

Example 16. The generator for a surgical instrument of Example 15,wherein the at least three electrical parameters associated with thetissue in contact with the RF instrument comprise an initial RFimpedance of the tissue, a minimum RF impedance of the tissue, and anamount of time in milliseconds that the RF impedance slope is ˜0.

Example 17. The generator for a surgical instrument of any one or moreof Examples 15 through 16, wherein the control circuit is furtherconfigured to collect data associated with the at least three electricalparameters in a predetermined amount of time.

Example 18. The generator for a surgical instrument of Example 17,wherein the predetermined amount of time comprises a first 0.75 secondsafter activation of the radio frequency (RF) instrument.

Example 19. The generator for a surgical instrument of any one or moreof Examples 15 through 18, wherein the control circuit is furtherconfigured to classify the tissue into a distinct group in live timeusing a support vector machine algorithm.

Example 20. The generator for a surgical instrument of Example 19,wherein the support vector machine algorithm comprises a linear basisfunction, a polynomial basis function, or a radial basis function.

Example 21. The generator for a surgical instrument of any one or moreof Examples 15 through 20, wherein the control circuit is furtherconfigured to apply an activation algorithm specific to each tissuegroup after the first period T1.

1. A method of classifying a tissue in live time, the method comprising:activating, by a processor or control circuit, a radio frequency (RF)instrument for a first period of time T1, wherein the RF instrumentcontacts the tissue; plotting, by the processor or control circuit, atleast three electrical parameters associated with the tissue in contactwith the RF instrument to classify the tissue into distinct groups; andapplying, by the processor or control circuit, a classificationalgorithm to classify the tissue into a distinct group in live time. 2.The method of claim 1, wherein plotting, by the processor or controlcircuit, at least three electrical parameters associated with the tissuein contact with the RF instrument comprises plotting, by the processoror control circuit, an initial RF impedance of the tissue, a minimum RFimpedance of the tissue, and an amount of time in milliseconds that theRF impedance slope is ˜0.
 3. The method of claim 1, further comprisingcollecting, by the processor or control circuit, data associated withthe at least three electrical parameters in a predetermined amount oftime.
 4. The method of claim 3, wherein collecting, by the processor orcontrol circuit, data associated with the at least three electricalparameters in a predetermined amount of time comprises collecting, bythe processor or control circuit, data associated with the at leastthree electrical parameters in within a first 0.75 seconds afteractivation of the radio frequency (RF) instrument.
 5. The method ofclaim 1, wherein applying, by the processor or control circuit, aclassification algorithm to classify the tissue into a distinct group inlive time comprises applying, by the processor or control circuit, aclassification algorithm to classify the tissue into a distinct group inlive time using a support vector machine algorithm.
 6. The method ofclaim 5, wherein applying, by the processor or control circuit, aclassification algorithm to classify the tissue into a distinct group inlive time using a support vector machine algorithm comprises applying,by the processor or control circuit, a classification algorithm toclassify the tissue into a distinct group in live time using a linearbasis function, a polynomial basis function, or a radial basis function.7. The method of claim 1, further comprising applying, by the processoror control circuit, an activation algorithm specific to each tissuegroup after the first period T1.
 8. A surgical instrument comprising: aradio frequency (RF) instrument comprising an end effector; and agenerator configured to supply power to the end effector, wherein thegenerator comprises a control circuit configured to: activate the radiofrequency (RF) instrument for a first period of time T1, wherein the RFinstrument contacts the tissue; plot at least three electricalparameters associated with the tissue in contact with the RF instrumentto classify the tissue into distinct groups; and apply a classificationalgorithm to classify the tissue into a distinct group in live time. 9.The surgical instrument of claim 8, wherein the at least threeelectrical parameters associated with the tissue in contact with the RFinstrument comprise an initial RF impedance of the tissue, a minimum RFimpedance of the tissue, and an amount of time in milliseconds that theRF impedance slope is ˜0.
 10. The surgical instrument of claim 8,wherein the control circuit is further configured to collect dataassociated with the at least three electrical parameters in apredetermined amount of time.
 11. The surgical instrument of claim 10,wherein the predetermined amount of time comprises a first 0.75 secondsafter activation of the radio frequency (RF) instrument.
 12. Thesurgical instrument of claim 8, wherein the control circuit is furtherconfigured to classify the tissue into a distinct group in live timeusing a support vector machine algorithm.
 13. The surgical instrument ofclaim 12, wherein the support vector machine algorithm comprises alinear basis function, a polynomial basis function, or a radial basisfunction.
 14. The surgical instrument of claim 8, wherein the controlcircuit is further configured to apply an activation algorithm specificto each tissue group after the first period T1.
 15. A generator for asurgical instrument, wherein the surgical instrument comprises a radiofrequency (RF) instrument comprising an end effector, the generatorcomprising: a control circuit configured to: activate the radiofrequency (RF) instrument for a first period of time T1, wherein the RFinstrument contacts a tissue; plot at least three electrical parametersassociated with the tissue in contact with the RF instrument to classifythe tissue into distinct groups; and apply a classification algorithm toclassify the tissue into a distinct group in live time.
 16. Thegenerator for a surgical instrument of claim 15, wherein the at leastthree electrical parameters associated with the tissue in contact withthe RF instrument comprise an initial RF impedance of the tissue, aminimum RF impedance of the tissue, and an amount of time inmilliseconds that the RF impedance slope is ˜0.
 17. The generator for asurgical instrument of claim 15, wherein the control circuit is furtherconfigured to collect data associated with the at least three electricalparameters in a predetermined amount of time.
 18. The generator for asurgical instrument of claim 17, wherein the predetermined amount oftime comprises a first 0.75 seconds after activation of the radiofrequency (RF) instrument.
 19. The generator for a surgical instrumentof claim 15, wherein the control circuit is further configured toclassify the tissue into a distinct group in live time using a supportvector machine algorithm.
 20. The generator for a surgical instrument ofclaim 19, wherein the support vector machine algorithm comprises alinear basis function, a polynomial basis function, or a radial basisfunction.
 21. The generator for a surgical instrument of claim 15,wherein the control circuit is further configured to apply an activationalgorithm specific to each tissue group after the first period T1.